Potential Environmental and Health Impacts of Florida Phophate Mining and Processing

6439 words (26 pages) Essay

23rd Sep 2019 Environmental Studies Reference this

Disclaimer: This work has been submitted by a university student.

Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of AUEssays.com.

Potential Environmental and Health Impacts of Florida Phophate Mining and Processing

Abstract:

Deposits of phosphate minerals are present throughout much of the United States while Florida currently contains the largest known deposits. Florida Phosphate mining occurs primarily in the central Florida area covering approximately 1.3 million acres of land known as the “Bone Valley.” United States continues to be one of the top phophate producing nations in the world as Florida continue to have large phophate reserves. With the rapid growth of phophate industry in Florida, environmental and health impacts have also increased. Though various precautionary measures have been undertaken prior to begin mining activities, significant impacts on water resources have been identified by few researchers. Air quality is also affected by Fluoride and radon gas emissions. Dust has been a continuous issue in phophate mining industry in Florida. This study evaluated the published information related to phosphate mining and processing in Florida.

(Key words: Phophate mining, beneficiation, environmental impacts, health impacts, Florida phophate deposits)

 

Introduction

Phosphates deposits are found in parts of the United States while Florida consists of the largest accessible phosphate deposits. Florida Phosphate mining is accountable for approximately 80 percent of phosphates used in United States as well as 25 percent world consumption. There are 27 phosphate mines in Florida covering above 430,000 acres in Florida.  This includes six active phosphate mines, six fully reclaimed mines and the rest of the mines are either not started or closed. (FDEP, 2018). Currently phosphate mining in Florida is mainly carried out in “Bone Valley” region which consists of the parts of Hardee, Hillsborough, Manatee, and Polk Counties utilizing approximately 1.3 million land area in Central Florida. About 65 % of United States phophate production came from Florida phosphates in 2010 (Jasinski, 2010). Currently Morocco is becoming the world leading phosphates producer due to the availability of large phophate reserves. However, United States will continue to be one of the leading phosphates producer in the world for another few decades due to the availability of extensive reserves in Florida (al Rawashde and Maxwell, 2011). Phosphate rocks in Florida has a sedimentary origin and believed to form during Neocene period (Lane, 1994). Though Florida phophate mining begun in 1880’s with the invention of black phosphates pebbles in peace river region, commercial mining was started in 1908 became the leading phophate producer (Pittman, 1990).  Technological advancements in phosphate mining has increased the mining efficiency over the last century. Variety of products such as fertilizer, animal feed, detergents and food and beverage products can be produced from phophate rock. However, fertilizer production is the most economically beneficial. (al Rawashde and Maxwell, 2011). There are number of environmental and health effects associated with Phophate mining in Florida. Phophate ore should generally undergo mining and benefaction process to produce usable phosphates. (Szilas,2002). These processes produce extensive amonuts of toxic and radiactive waste which can affect the environment and human health. It is estimated that over 30 million tons of radioactive phosphogypsum byproduct is produced annually in Florida (FIPR, 2000).A regulation has passed in 1975 to regulate the large-scale phosphate mining in Florida. As a result, valid permits are now required to start any mining activity in Florida lands. Objective of this study is to understand the current status of phosphate mining in Florida and to identify the potential environmental and health impacts of Florida phosphate mining and beneficiation process.

Methodology

This paper was based on the published information related to phosphate mining and beneficiation in the state of Florida. Published information was reviewed to identify the history of Florida phosphate mining, the beneficiation process involved, the chemical composition of phosphate rocks in Florida, potential environmental and health risks associated with the phophate mining and beneficiation activities. Literature search was not limited to a particular time period, however high priority was given to the articles related to Florida phophate mining.  The review was organized into a results section, discussion section and a conclusion section. The result section includes the information related to the origin and distribution of phosphates rocks in Florida, the history of phosphates mining in Florida, phophate mining and beneficiation process, Radioactivity associated with Phosphate mining and fertilizer production in Florida and Waste products and disposal methods.  The discussion section consists of the environmental impacts of phophate mining and processing with the emphasis given to the impacts on water resources, air quality, human health and land/soil and biodiversity. 

Results

Origin and distribution of phosphates rocks in Florida

Central Florida and Northern Florida have identified to consists of economically feasible phosphates deposits known as Francolite (Carbonate fluorapatite). According to Riggs (1979), unusual combination of geological features during Neocene period is responsible to form economically viable phosphates deposits in this region. Combination of these conditions have made Florida the most fertile phosphate region in the world. (Van Kauwenbergh, et al, 1990). According to Florida Industrial and Phosphate Research Institute (FIPR) three most common groups of minerals found in Florida Phosphates include Phosphatic minerals, Clay minerals, Quarts or Sand. Different particle size of these minerals provides an easy separation and that has given Florida phosphates its uniqueness compared to other phosphates deposits in the world. There is no accurate estimation about the available phosphates reserves in Florida as they are varying over the time. However, Van Kauwenbergh et al (2010), stated that some believe that there is a possibility of increasing phosphates reserves in Florida over next few decades to a peak whereas International Fertilizer Development Centers estimation suggests that world phosphates reserves will only stay for another 300-400 years.

History of Phosphate mining in Florida

Phosphates mining in Florida has begun in 1888, with the invention of phosphate pebbles in Peace River in central Florida. By the year 1908, phosphates mining companies have started their operation near Peace River region to mine phosphate rock or land pebble, making Florida the leading phosphate producer in US (Pittman, 1990). However, large amount of mined phosphates was not useful as there was no proper techniques to separate different sizes of rocks at that time. Mining efficiency has significantly increased with the use of electric draglines. However, considerable fraction of mined phosphates was still useless due to lack of separation techniques. Invention of Floatation techniques in 1927 has lead Florida phosphate mining into a different direction as it significantly increased the quantity of usable phosphates minerals from its matrix. (Pittman, 1990). 

Phosphate mining and beneficiation process in Florida

Source: (FIPR,2018)

Prior to any mining activity, the thickness of overburden and the matrix is determined through exploratory core analysis. This helps to identify the availability of economically feasible phosphate rock below ground.  Number of precautions are taken prior to conduct any commercial mining activity to minimize the possible impacts to the environment. This includes wildlife surveys, relocating of threatened and endangered species, land clearing with minimal impacts to neighboring unmined lands, and certain measures to protect water quality (EPA, 2018).

Check Your Work for Plagiarism

Viper is a quick and easy way to check your work for plagiarism. The online scanning system matches your work against over 5 Billion online sources within seconds.

Try Viper Today!

Florida phosphate mining is primarily based on strip mining process which results in digging up thousands of acres of land annually. Earth layer lying top of the phosphate which is known as the “Overburden” is removed to uncover the phosphate reserve which is known as “matrix”. About 15 to 30 feet of earth is scooped up using large electric draglines and placed it on spoil piles to the side of the mine pit. Matrix material is then lifted out and dumped into another pit where it is blasted with high pressure water to produce a slurry. The slurry is then pumped in to the beneficiation plant where mechanical process is used to separate matrix into its individual components such as Phosphate rock, clay, and sand.  The beneficiation plant is generally located in few miles away from the manning site. (Beavers et al., 2013).

Beneficiation is defined as the mechanical separation of matrix into its individual components. This process does not change the chemical composition of minerals. Floatation is one of the technologies used today to separate valuable minerals from its phosphate ore during the beneficiation process. This modern technology has been discovered in 20th century and it has significantly increased the efficiency of the beneficiation process (FIPR,2018). Beneficiation process separates phosphate matrix in to clay, sand and phosphate rock. Large impoundment areas known as “Clay settling areas” are used to settle clay from the beneficiation while sand from beneficiation known as “sand tailing” is sent back to the mined areas for later use in reclamation or fill mine pits. Once the mechanical separation of minerals is completed, chemical separation of minerals is begun in another facility. Chemically processed phosphate minerals are then used to manufacture fertilizer and other products. Mining and Mitigation program is not responsible for regulating chemical processing of phosphate minerals (Beavers, 2013). Processing of phophate is carried out in two ways known as wet processing and dry thermal processing (Reta,2018). Wet processing which involves Sulfuric acid treatment is the commonly used method for phophate fertilizer production in Florida. This reaction produces phosphoric acid which then be combined with ammonia to produce di ammonium phophate (DAP) or monoammonium phophate (MAP) (al Rawashde and Maxwell, 2011).  The fertilizer is then transported by train to port or other distribution areas throughout the US.

 

Radioactivity associated with Phosphate mining and fertilizer production in Florida

Radioactive elements such as uranium and radium are found in most phosphates with sedimentary origin. However, their radioactivity will not significantly affect the environment unless we disturb or excavate those underground phophate deposits (Cioroianu et al., 2001). Phosphates mining and beneficiation in Florida may increase the radioactivity in the environment as these activities disturb the natural equilibrium between Uranium and Radium or Radon 222.  About 85% of exploited natural phosphates for fertilizer production that derived from sedimentary origin is believed to contain uranium and its radioactive daughters. (Cioroianu et al., 2001). Following table illustrates the amount of Uranium and Radium 226 in natural phosphates in few phophate mining regions in the world including Florida. The data shows Florida phophate deposits consists of considerable radioactivity from both Uranium and Radium compared with other regions in the World.

Phophate deposit from

Type

U content mg/kg

226Ra content Bq/kg

Florida

Sedimentary

100-150

750-1500

Florida

Sedimentary

80-100

600-800

Carolina

Sedimentary

80-120

600-1000

Morocco

Sedimentary

100-160

800-1600

Tunis

Sedimentary

30-50

250-350

Algeria

Sedimentary

100-120

700-850

Israel

Sedimentary

80-140

800-1200

Jordan

Sedimentary

80-110

800-900

Togo

Sedimentary

100-110

950-1000

Senegal

Sedimentary

100-120

950-1100

Curacao

Sedimentary

20

Kola

Volcanic

20

70

Source: Cioroianu et al., (2001).

Phophate rock is treated with sulfuric acid during the fertilizer production from natural phophate rock. This reaction produces phosphoric acid and phosphogypsum. Phosphoric acid is further treated to produce fertilizer. This intermediate product contains certain amount of radioactivity that was found in natural phophate rock used to initiate the process. Cioroianu et al., (2001) stated that most of the radioactivity found in natural phophate rock of sedimentary origin will be transferred to the ultimate product during the process of fertilizer production. Following table illustrates the concentration of uranium and radium in Phosphoric Acid.

Phophate rock used

Uranium mg/L

226Ra Bq/L

Florida

120-140

40-70

Jordan

80-100

30-50

Morocco

120-160

30-60

Israel

90-110

40-50

Togo

100-110

60

Senegal

100-100

70

Kola

5-10

Syria

70-90

60

Egypt

80-100

50

Tunis

40-60

40

Algeria

80-100

60

Source: Cioroianu et al., (2001)

Following table illustrates the content of Uranium and Radium found in phosphogypsum.

Phophate rock used

Uranium mg/kg

226Ra Bq/kg

Florida

10-20

500-1200

Jordan

5-10

500-1000

Morocco

10-15

600-1300

Israel

10-20

600-1200

Tunis

5-8

300-400

Kola

60-100

Togo

10

700-1100

Source: Cioroianu et al., (2001)

 

 

Waste products and disposal methods

Phophate mining and beneficiation results large amount of waste which can cause severe environmental impacts unless properly disposed (UNEP,2001). Phosphogypsum is produced as a byproduct during the process of fertilizer production using the phosphate rock. It is formed when phosphate rock is treated with sulfuric acid to produce phosphoric acid as shown in the following word reaction.

                               Phosphate Rock + Sulfuric Acid = Phosphoric Acid + Gypsum

For every ton of phosphoric acid product produced, approximately 5 tons of phosphogypsum (CaSO4) are produced. Though phosphogypsum has many uses, EPA has banned most of its use in 1992 as phosphogypsum found to contain high levels of radioactivity and harmful trace minerals. As a result, large quantity of phosphogypsum stacks can be found throughout the phophate mining district in Central Florida. (FIPR,2018). Process water produced from phophate mining and processing are stored in large impoundment areas and reuse later in the process. Sometimes, the liquid wastes are released in to rivers or oceans after treating to reduce acidity and clay and sand is used to refill the mine pits (UNEP, 2001).

Data Source:  People for Protecting Peace River, INC. 3PR (2015).

Regulation of the Florida Phosphate Industry

Several State (Florida Department of Environment Protection Agency-FDEP) and Federal regulatory agencies (Army Corps of Engineers and Environment Protection Agency) are involved with Florida phophate mining industry. These agencies are not only responsible for regulating mining industry, but also trying to minimize the impacts on water resources through a permitting program called “Environmental Resource Permitting (ERP)”. This program controls the activities related to Florida’s surface waters such as surface water flows and storm water runoff. It also manages digging and filling operations on surface water bodies as these activities can impact the natural hydrology of the entire region.  Therefore, mining industries require to obtain mainly two permits known as Environmental Resource Permit (ERP) and Wetland Resource Permit (WRP) before starting any mining activity in Florida. (EPA,2018). In addition to these permitting requirements, mining companies should also pay taxes for the using Florida phosphates deposits for commercial purposes.

Discussion:

Florida phophate mining involves variety of activities such as land clearing, extraction, mechanical and chemical processing, waste disposal etc. Each of these activities may have impacts on water quality, air quality, land and human health. Much of these effects are localized and limited to a particular mining site. However, the type and severity of those impacts may differ from site to site based on the nature of phophate ore and overburden, climatic conditions, neighboring ecosystems and whether the land surface consists of wetlands, plains, hills or mountains. (UNEP,2001)

Impacts on Water Resources

Water resources can be impacted mainly in two ways. High water use and land use changes can impact natural hydrology in the area while water quality can be affected by the industrial discharges into waterways (Beavers.,2013). Few studies have stated that Florida phophate mining has caused significant changes to local hydrology in the region. Lewlling & Wylie (1993) studied the impacts on phophate mining on ground water and surface water resources in west central Florida.  They had compared the hydrologic aspects and water quality of few unmined basins in the area with mined and reclaimed basins and found out that peak high runoff rates in mined basins compared to unmined basins. They have observed that type of filling used during reclamation influences the hydrological characteristics in the region. They also noticed high levels of certain chemicals such as lead, iron, sulfate, dissolved solids as well as high levels of radioactivity in reclaimed basins. Another study conducted by Miller et al., (1978) suggested that mining activities can affect the natural flow rates of streams as a result of releasing large quantity of water from mining activities. Erwin et al.,1997 stated that impacts of mining activities on local hydrology is obvious as digging the earth and refilling with different material can change structure of shallow acquifer. As reclaimed areas contain high amount of clay and silt, it affects the acquifer recharge rate from rainfall. This reduces the infiltration rate and increase the amount of water retained above ground.  The study conducted by PBS & J., (2007) found that Peace River Watershed had been affected by urbanization, agriculture and mining in various ways. Amount of ground water use in mining was reduced since the development of storing and reusing techniques in late 1970s. However, mining affects the characteristics of land surface and soils as it requires storing large quantity of water in some areas while faster release in other areas.

Low Cost Online Plagiarism Checker

Viper is a quick and easy way to check your work for plagiarism. The online scanning system matches your work against over 5 Billion online sources within seconds.

Try Viper Today!

Miller & Sutcliffe (1984) conducted a study to identify the impacts of phosphates mining on the ground water quality in central Florida emphasizing the effects from phosphogypsum stacks and nearby ponds.  His findings indicated a clear difference between mine water chemistry and natural ground water chemistry. Because extremely acidic mine water consisted of a solute concentration of 28,000mg/L with a pH of 1.4 to 1.8 units. Major solute components were sodium, phophate, fluorosilicate, hydrogen and sulfate irons while ground water contains only dissolved solids less than 500 mg/L and calcium bicarbonate with pH about 7.0 units. Most mobile ions in contaminated mine water was Sodium and Sulfate. Movement of other constituents such as radionuclides, fluorosilicates, phosphates and trace metals were regulated by the extent of acid neutralization when reacting with acquifer material thus limited only to the areas surrounding to the source. Other useful trace elements found near gypsum stacks include iodide, bromide and ammonium. Phosphorous, trace metals and radioactive chemicals were found in mined slime. However, slime ponds were capable of retaining most of these chemicals thus preventing water contamination. Another study by Beavers et al (2013) on phophate mining in Florida, illustrated that accidental or intentional spills of process mine waters into local water ways can affect the surface water quality in nearby areas. Process water are stored on the top of phosphogypsum stacks and reuse for mining activities.  However, during heavy rains, these waters must be discharged to prevent overflowing. Process water contains number of ions such as Sulfate and Fluoride and it is normally acidic with pH near 1.75 (Foley and Pollock, 2000). Therefore, process water is treated with lime to reduce acidity before discharging. Despite liming, process water may not meet the required water quality for discharge to the environment (Jardine et al., 2005).   Several studies have examined the impacts of Fluoride toxicity associated with phophate mining on water quality. A study conducted on Alafia and Peace River basin by Toler (1967) found that high fluoride levels in Alafia and Peace rivers were associated with mined waters from phophate industries which could contaminate headwater tributaries.  

Accidental and unintentional release of phosphogypsum and acidic water into the environment is a serious problem in Florida phophate mining. About 4 million cubic feet of phosphogypsum and acidic water has been discharged into the acquifer contaminating ground water because of opening a large sink hole in Polk County Florida in 1994 (Galloway et al., 2013).  Another accident in 1997, has discharged about 5 million gallons of acidic water in to surrounding wetlands due to a breakage of a phosphogypsum dam resulting 50,000 to 3,000,000 fish kills in downstream waters (Foley and Pollock, 2000).  Another incident in 2004, released 65000 process water into the Hillsborough Bay affecting coastal ecosystems.  (PAS and LES, 2005).  

Impacts on Air quality

Air quality can be impacted by number of gas emissions and dust from mining activities. Phophate mining is greatly associated with fluoride emissions and radon gas emissions (UNEP, 2001). Fluoride is chemically bound to commonly found phophate mineral (fluorapatite) in Florida. Minor quantities of Fluoride are good for human health while higher doses negatively affect the health of our teeth and bones. However, current fluoride emissions are very low due to the improvement of technologies to trap them by most of phosphates mining industries in Florida (FIPR, 2018). Radon is another air polluting gas emitted from mining activities. Florida phosphates deposits contain radioactive elements such as Uranium. Radon gas is an intermediate produced during the natural decay series Uranium to Lead. Radon is a colorless and odorless gas with no reactivity. However, it can be dissolved in water and organic solvents.  EPA’s permitted radon levels in the atmosphere is 4 picoCuries/Liter (EPA,2016). Phophate mining areas may have higher radon levels compared to other areas as mining brings radioactive elements into the surface.  Therefore, phophate mining increases outdoor radon levels However, this increase does not cause any significant threat to human health as radon gas quickly disseminate in the atmosphere into undetectable concentrations. (FIPR,2018).  Dust can be generated from almost all mining activities including crushing phophate rock, product storage, transportation of ore, phosphogypsum stacks (Chernaik et al., 2010). Dust may also contain of radioactive particles. However, the use of wet process has significantly lowered the amount of dust emitted to the environment while dust produced from processing and product storage has greatly reduced since 1980’s with the use of oil coating its products (FIPR.2018).

 

Impacts on human health

About 57 trace elements in phophate rocks have been identified to contain various levels of toxicity. Out of those 57 elements, Be, As, Cd, Hg and Ra are recognized as extremely toxic (Chen., 2015). Following table illustrates the degree of toxicity of various elements found in phophate rock.

Associated elements found in phophate rock

 

Degree of toxicity

Be, As, Cd, Hg, Tl, Ra

F, Cl (Cl2), Cr, Ba, Gd, Yb, Pb

Li, Ni, Cu, Ga, Sn, Sb, Te, La, Ce, Pr, Nd, Sm, Tb, Ho, Bi, Th, U

Ca, V, Mn, Fe, Zn, Ge, Mo, Lu

Mg, S, Ca, Sc, Co, Se, Sr, Y, Zr, Nb, Ag, In, I, Dy, Eu, Er, Tm, Hf, Au

Extreme

High

Moderate

Low

Negligible

Data Source: Reta (2018)

More than 21000 lung cancer deaths per year in United States are associated with radon gas. Decay products of radon gas can enhance lung cancers by destroying cells in the lung tissues. In Florida, one in 5 homes tested have been identified to exceed the EPA permissible radon levels of 4pCi/L. Since radon is a gas contain in soil, it can enter a building through flooring. Once it is entered to a building, it can trap and build up on closed buildings into a higher concentration than outside air. Since radon is colorless and odorless gas, there is no way to identify it rather than testing (“Florida Health”,2018). According to the EPA radon zones map, none of the Florida counties have a predicted average indoor radon screening level greater than EPA standard concentration of 4 pCi/L. However, few counties in North, Central and South East Florida have a moderate radon potential which contains radon screening level between 2 and 4pCi/L. Most of the other counties indoor radon levels are below 2pCi/L.

Data Source: Map of Radon Zones in Florida based on EPA data.

Impacts on land/soil and Biodiversity

As Florida phophate mining is a surface or strip-mining process which can impact large surface area of the land causing more environmental damage compared to underground mining (Dudka,1997). During the exploration, land can be disturbed in variety of ways including removal of vegetation, building camps and access roads, drilling activities. Clearing of vegetation may have impact on local hydrological cycle, habitats of variety of species, thus reducing the biodiversity in the area. Construction activities may have more impact on land through earth works. During extraction, land and soil gets further disturbed by the removal of vegetation and top soil, extraction of large quantity of earth, depositing overburden, building waste dumping areas and clay settling ponds (UNEP,2001).

Conclusion

Environmental impacts of phophate mining were far wide to be covered in this review. However, I was able to address the impacts on water resources, air quality and human health. Several studied have been conducted to assess the impacts of phophate mining and processing on Water resources in Florida.  Based on those studies, it can be concluded that phophate mining has a significant impact on water resources. According to those studies phophate mining affects the local hydrology of the area by utilizing large quantity of water. It also changes the landscape of the areas which eventually affects the natural flow patterns. Few other studies conducted to assess the impacts of phophate mining on water quality have suggested that discharges of acid mine water into local waterways change the water quality. Those studied have mostly concerned about the discharge of acid mine water into surrounding wetlands and streams, release of radioactive and toxic metals into the environment. Air quality was affected mainly by Fluoride and radon gas emission. Dust was a common issue as it was produced throughout all the mining activities. Human health can be impacted mostly by toxic metals and radioactive elements as phophate products were mainly composed of Pb, Cd, Cr, As, U and Ra.

References:

Potential Environmental and Health Impacts of Florida Phophate Mining and Processing

Abstract:

Deposits of phosphate minerals are present throughout much of the United States while Florida currently contains the largest known deposits. Florida Phosphate mining occurs primarily in the central Florida area covering approximately 1.3 million acres of land known as the “Bone Valley.” United States continues to be one of the top phophate producing nations in the world as Florida continue to have large phophate reserves. With the rapid growth of phophate industry in Florida, environmental and health impacts have also increased. Though various precautionary measures have been undertaken prior to begin mining activities, significant impacts on water resources have been identified by few researchers. Air quality is also affected by Fluoride and radon gas emissions. Dust has been a continuous issue in phophate mining industry in Florida. This study evaluated the published information related to phosphate mining and processing in Florida.

(Key words: Phophate mining, beneficiation, environmental impacts, health impacts, Florida phophate deposits)

 

Introduction

Phosphates deposits are found in parts of the United States while Florida consists of the largest accessible phosphate deposits. Florida Phosphate mining is accountable for approximately 80 percent of phosphates used in United States as well as 25 percent world consumption. There are 27 phosphate mines in Florida covering above 430,000 acres in Florida.  This includes six active phosphate mines, six fully reclaimed mines and the rest of the mines are either not started or closed. (FDEP, 2018). Currently phosphate mining in Florida is mainly carried out in “Bone Valley” region which consists of the parts of Hardee, Hillsborough, Manatee, and Polk Counties utilizing approximately 1.3 million land area in Central Florida. About 65 % of United States phophate production came from Florida phosphates in 2010 (Jasinski, 2010). Currently Morocco is becoming the world leading phosphates producer due to the availability of large phophate reserves. However, United States will continue to be one of the leading phosphates producer in the world for another few decades due to the availability of extensive reserves in Florida (al Rawashde and Maxwell, 2011). Phosphate rocks in Florida has a sedimentary origin and believed to form during Neocene period (Lane, 1994). Though Florida phophate mining begun in 1880’s with the invention of black phosphates pebbles in peace river region, commercial mining was started in 1908 became the leading phophate producer (Pittman, 1990).  Technological advancements in phosphate mining has increased the mining efficiency over the last century. Variety of products such as fertilizer, animal feed, detergents and food and beverage products can be produced from phophate rock. However, fertilizer production is the most economically beneficial. (al Rawashde and Maxwell, 2011). There are number of environmental and health effects associated with Phophate mining in Florida. Phophate ore should generally undergo mining and benefaction process to produce usable phosphates. (Szilas,2002). These processes produce extensive amonuts of toxic and radiactive waste which can affect the environment and human health. It is estimated that over 30 million tons of radioactive phosphogypsum byproduct is produced annually in Florida (FIPR, 2000).A regulation has passed in 1975 to regulate the large-scale phosphate mining in Florida. As a result, valid permits are now required to start any mining activity in Florida lands. Objective of this study is to understand the current status of phosphate mining in Florida and to identify the potential environmental and health impacts of Florida phosphate mining and beneficiation process.

Methodology

This paper was based on the published information related to phosphate mining and beneficiation in the state of Florida. Published information was reviewed to identify the history of Florida phosphate mining, the beneficiation process involved, the chemical composition of phosphate rocks in Florida, potential environmental and health risks associated with the phophate mining and beneficiation activities. Literature search was not limited to a particular time period, however high priority was given to the articles related to Florida phophate mining.  The review was organized into a results section, discussion section and a conclusion section. The result section includes the information related to the origin and distribution of phosphates rocks in Florida, the history of phosphates mining in Florida, phophate mining and beneficiation process, Radioactivity associated with Phosphate mining and fertilizer production in Florida and Waste products and disposal methods.  The discussion section consists of the environmental impacts of phophate mining and processing with the emphasis given to the impacts on water resources, air quality, human health and land/soil and biodiversity. 

Results

Origin and distribution of phosphates rocks in Florida

Central Florida and Northern Florida have identified to consists of economically feasible phosphates deposits known as Francolite (Carbonate fluorapatite). According to Riggs (1979), unusual combination of geological features during Neocene period is responsible to form economically viable phosphates deposits in this region. Combination of these conditions have made Florida the most fertile phosphate region in the world. (Van Kauwenbergh, et al, 1990). According to Florida Industrial and Phosphate Research Institute (FIPR) three most common groups of minerals found in Florida Phosphates include Phosphatic minerals, Clay minerals, Quarts or Sand. Different particle size of these minerals provides an easy separation and that has given Florida phosphates its uniqueness compared to other phosphates deposits in the world. There is no accurate estimation about the available phosphates reserves in Florida as they are varying over the time. However, Van Kauwenbergh et al (2010), stated that some believe that there is a possibility of increasing phosphates reserves in Florida over next few decades to a peak whereas International Fertilizer Development Centers estimation suggests that world phosphates reserves will only stay for another 300-400 years.

History of Phosphate mining in Florida

Phosphates mining in Florida has begun in 1888, with the invention of phosphate pebbles in Peace River in central Florida. By the year 1908, phosphates mining companies have started their operation near Peace River region to mine phosphate rock or land pebble, making Florida the leading phosphate producer in US (Pittman, 1990). However, large amount of mined phosphates was not useful as there was no proper techniques to separate different sizes of rocks at that time. Mining efficiency has significantly increased with the use of electric draglines. However, considerable fraction of mined phosphates was still useless due to lack of separation techniques. Invention of Floatation techniques in 1927 has lead Florida phosphate mining into a different direction as it significantly increased the quantity of usable phosphates minerals from its matrix. (Pittman, 1990). 

Phosphate mining and beneficiation process in Florida

Source: (FIPR,2018)

Prior to any mining activity, the thickness of overburden and the matrix is determined through exploratory core analysis. This helps to identify the availability of economically feasible phosphate rock below ground.  Number of precautions are taken prior to conduct any commercial mining activity to minimize the possible impacts to the environment. This includes wildlife surveys, relocating of threatened and endangered species, land clearing with minimal impacts to neighboring unmined lands, and certain measures to protect water quality (EPA, 2018).

Florida phosphate mining is primarily based on strip mining process which results in digging up thousands of acres of land annually. Earth layer lying top of the phosphate which is known as the “Overburden” is removed to uncover the phosphate reserve which is known as “matrix”. About 15 to 30 feet of earth is scooped up using large electric draglines and placed it on spoil piles to the side of the mine pit. Matrix material is then lifted out and dumped into another pit where it is blasted with high pressure water to produce a slurry. The slurry is then pumped in to the beneficiation plant where mechanical process is used to separate matrix into its individual components such as Phosphate rock, clay, and sand.  The beneficiation plant is generally located in few miles away from the manning site. (Beavers et al., 2013).

Beneficiation is defined as the mechanical separation of matrix into its individual components. This process does not change the chemical composition of minerals. Floatation is one of the technologies used today to separate valuable minerals from its phosphate ore during the beneficiation process. This modern technology has been discovered in 20th century and it has significantly increased the efficiency of the beneficiation process (FIPR,2018). Beneficiation process separates phosphate matrix in to clay, sand and phosphate rock. Large impoundment areas known as “Clay settling areas” are used to settle clay from the beneficiation while sand from beneficiation known as “sand tailing” is sent back to the mined areas for later use in reclamation or fill mine pits. Once the mechanical separation of minerals is completed, chemical separation of minerals is begun in another facility. Chemically processed phosphate minerals are then used to manufacture fertilizer and other products. Mining and Mitigation program is not responsible for regulating chemical processing of phosphate minerals (Beavers, 2013). Processing of phophate is carried out in two ways known as wet processing and dry thermal processing (Reta,2018). Wet processing which involves Sulfuric acid treatment is the commonly used method for phophate fertilizer production in Florida. This reaction produces phosphoric acid which then be combined with ammonia to produce di ammonium phophate (DAP) or monoammonium phophate (MAP) (al Rawashde and Maxwell, 2011).  The fertilizer is then transported by train to port or other distribution areas throughout the US.

 

Radioactivity associated with Phosphate mining and fertilizer production in Florida

Radioactive elements such as uranium and radium are found in most phosphates with sedimentary origin. However, their radioactivity will not significantly affect the environment unless we disturb or excavate those underground phophate deposits (Cioroianu et al., 2001). Phosphates mining and beneficiation in Florida may increase the radioactivity in the environment as these activities disturb the natural equilibrium between Uranium and Radium or Radon 222.  About 85% of exploited natural phosphates for fertilizer production that derived from sedimentary origin is believed to contain uranium and its radioactive daughters. (Cioroianu et al., 2001). Following table illustrates the amount of Uranium and Radium 226 in natural phosphates in few phophate mining regions in the world including Florida. The data shows Florida phophate deposits consists of considerable radioactivity from both Uranium and Radium compared with other regions in the World.

Phophate deposit from

Type

U content mg/kg

226Ra content Bq/kg

Florida

Sedimentary

100-150

750-1500

Florida

Sedimentary

80-100

600-800

Carolina

Sedimentary

80-120

600-1000

Morocco

Sedimentary

100-160

800-1600

Tunis

Sedimentary

30-50

250-350

Algeria

Sedimentary

100-120

700-850

Israel

Sedimentary

80-140

800-1200

Jordan

Sedimentary

80-110

800-900

Togo

Sedimentary

100-110

950-1000

Senegal

Sedimentary

100-120

950-1100

Curacao

Sedimentary

20

Kola

Volcanic

20

70

Source: Cioroianu et al., (2001).

Phophate rock is treated with sulfuric acid during the fertilizer production from natural phophate rock. This reaction produces phosphoric acid and phosphogypsum. Phosphoric acid is further treated to produce fertilizer. This intermediate product contains certain amount of radioactivity that was found in natural phophate rock used to initiate the process. Cioroianu et al., (2001) stated that most of the radioactivity found in natural phophate rock of sedimentary origin will be transferred to the ultimate product during the process of fertilizer production. Following table illustrates the concentration of uranium and radium in Phosphoric Acid.

Phophate rock used

Uranium mg/L

226Ra Bq/L

Florida

120-140

40-70

Jordan

80-100

30-50

Morocco

120-160

30-60

Israel

90-110

40-50

Togo

100-110

60

Senegal

100-100

70

Kola

5-10

Syria

70-90

60

Egypt

80-100

50

Tunis

40-60

40

Algeria

80-100

60

Source: Cioroianu et al., (2001)

Following table illustrates the content of Uranium and Radium found in phosphogypsum.

Phophate rock used

Uranium mg/kg

226Ra Bq/kg

Florida

10-20

500-1200

Jordan

5-10

500-1000

Morocco

10-15

600-1300

Israel

10-20

600-1200

Tunis

5-8

300-400

Kola

60-100

Togo

10

700-1100

Source: Cioroianu et al., (2001)

 

 

Waste products and disposal methods

Phophate mining and beneficiation results large amount of waste which can cause severe environmental impacts unless properly disposed (UNEP,2001). Phosphogypsum is produced as a byproduct during the process of fertilizer production using the phosphate rock. It is formed when phosphate rock is treated with sulfuric acid to produce phosphoric acid as shown in the following word reaction.

                               Phosphate Rock + Sulfuric Acid = Phosphoric Acid + Gypsum

For every ton of phosphoric acid product produced, approximately 5 tons of phosphogypsum (CaSO4) are produced. Though phosphogypsum has many uses, EPA has banned most of its use in 1992 as phosphogypsum found to contain high levels of radioactivity and harmful trace minerals. As a result, large quantity of phosphogypsum stacks can be found throughout the phophate mining district in Central Florida. (FIPR,2018). Process water produced from phophate mining and processing are stored in large impoundment areas and reuse later in the process. Sometimes, the liquid wastes are released in to rivers or oceans after treating to reduce acidity and clay and sand is used to refill the mine pits (UNEP, 2001).

Data Source:  People for Protecting Peace River, INC. 3PR (2015).

Regulation of the Florida Phosphate Industry

Several State (Florida Department of Environment Protection Agency-FDEP) and Federal regulatory agencies (Army Corps of Engineers and Environment Protection Agency) are involved with Florida phophate mining industry. These agencies are not only responsible for regulating mining industry, but also trying to minimize the impacts on water resources through a permitting program called “Environmental Resource Permitting (ERP)”. This program controls the activities related to Florida’s surface waters such as surface water flows and storm water runoff. It also manages digging and filling operations on surface water bodies as these activities can impact the natural hydrology of the entire region.  Therefore, mining industries require to obtain mainly two permits known as Environmental Resource Permit (ERP) and Wetland Resource Permit (WRP) before starting any mining activity in Florida. (EPA,2018). In addition to these permitting requirements, mining companies should also pay taxes for the using Florida phosphates deposits for commercial purposes.

Discussion:

Florida phophate mining involves variety of activities such as land clearing, extraction, mechanical and chemical processing, waste disposal etc. Each of these activities may have impacts on water quality, air quality, land and human health. Much of these effects are localized and limited to a particular mining site. However, the type and severity of those impacts may differ from site to site based on the nature of phophate ore and overburden, climatic conditions, neighboring ecosystems and whether the land surface consists of wetlands, plains, hills or mountains. (UNEP,2001)

Impacts on Water Resources

Water resources can be impacted mainly in two ways. High water use and land use changes can impact natural hydrology in the area while water quality can be affected by the industrial discharges into waterways (Beavers.,2013). Few studies have stated that Florida phophate mining has caused significant changes to local hydrology in the region. Lewlling & Wylie (1993) studied the impacts on phophate mining on ground water and surface water resources in west central Florida.  They had compared the hydrologic aspects and water quality of few unmined basins in the area with mined and reclaimed basins and found out that peak high runoff rates in mined basins compared to unmined basins. They have observed that type of filling used during reclamation influences the hydrological characteristics in the region. They also noticed high levels of certain chemicals such as lead, iron, sulfate, dissolved solids as well as high levels of radioactivity in reclaimed basins. Another study conducted by Miller et al., (1978) suggested that mining activities can affect the natural flow rates of streams as a result of releasing large quantity of water from mining activities. Erwin et al.,1997 stated that impacts of mining activities on local hydrology is obvious as digging the earth and refilling with different material can change structure of shallow acquifer. As reclaimed areas contain high amount of clay and silt, it affects the acquifer recharge rate from rainfall. This reduces the infiltration rate and increase the amount of water retained above ground.  The study conducted by PBS & J., (2007) found that Peace River Watershed had been affected by urbanization, agriculture and mining in various ways. Amount of ground water use in mining was reduced since the development of storing and reusing techniques in late 1970s. However, mining affects the characteristics of land surface and soils as it requires storing large quantity of water in some areas while faster release in other areas.

Miller & Sutcliffe (1984) conducted a study to identify the impacts of phosphates mining on the ground water quality in central Florida emphasizing the effects from phosphogypsum stacks and nearby ponds.  His findings indicated a clear difference between mine water chemistry and natural ground water chemistry. Because extremely acidic mine water consisted of a solute concentration of 28,000mg/L with a pH of 1.4 to 1.8 units. Major solute components were sodium, phophate, fluorosilicate, hydrogen and sulfate irons while ground water contains only dissolved solids less than 500 mg/L and calcium bicarbonate with pH about 7.0 units. Most mobile ions in contaminated mine water was Sodium and Sulfate. Movement of other constituents such as radionuclides, fluorosilicates, phosphates and trace metals were regulated by the extent of acid neutralization when reacting with acquifer material thus limited only to the areas surrounding to the source. Other useful trace elements found near gypsum stacks include iodide, bromide and ammonium. Phosphorous, trace metals and radioactive chemicals were found in mined slime. However, slime ponds were capable of retaining most of these chemicals thus preventing water contamination. Another study by Beavers et al (2013) on phophate mining in Florida, illustrated that accidental or intentional spills of process mine waters into local water ways can affect the surface water quality in nearby areas. Process water are stored on the top of phosphogypsum stacks and reuse for mining activities.  However, during heavy rains, these waters must be discharged to prevent overflowing. Process water contains number of ions such as Sulfate and Fluoride and it is normally acidic with pH near 1.75 (Foley and Pollock, 2000). Therefore, process water is treated with lime to reduce acidity before discharging. Despite liming, process water may not meet the required water quality for discharge to the environment (Jardine et al., 2005).   Several studies have examined the impacts of Fluoride toxicity associated with phophate mining on water quality. A study conducted on Alafia and Peace River basin by Toler (1967) found that high fluoride levels in Alafia and Peace rivers were associated with mined waters from phophate industries which could contaminate headwater tributaries.  

Accidental and unintentional release of phosphogypsum and acidic water into the environment is a serious problem in Florida phophate mining. About 4 million cubic feet of phosphogypsum and acidic water has been discharged into the acquifer contaminating ground water because of opening a large sink hole in Polk County Florida in 1994 (Galloway et al., 2013).  Another accident in 1997, has discharged about 5 million gallons of acidic water in to surrounding wetlands due to a breakage of a phosphogypsum dam resulting 50,000 to 3,000,000 fish kills in downstream waters (Foley and Pollock, 2000).  Another incident in 2004, released 65000 process water into the Hillsborough Bay affecting coastal ecosystems.  (PAS and LES, 2005).  

Impacts on Air quality

Air quality can be impacted by number of gas emissions and dust from mining activities. Phophate mining is greatly associated with fluoride emissions and radon gas emissions (UNEP, 2001). Fluoride is chemically bound to commonly found phophate mineral (fluorapatite) in Florida. Minor quantities of Fluoride are good for human health while higher doses negatively affect the health of our teeth and bones. However, current fluoride emissions are very low due to the improvement of technologies to trap them by most of phosphates mining industries in Florida (FIPR, 2018). Radon is another air polluting gas emitted from mining activities. Florida phosphates deposits contain radioactive elements such as Uranium. Radon gas is an intermediate produced during the natural decay series Uranium to Lead. Radon is a colorless and odorless gas with no reactivity. However, it can be dissolved in water and organic solvents.  EPA’s permitted radon levels in the atmosphere is 4 picoCuries/Liter (EPA,2016). Phophate mining areas may have higher radon levels compared to other areas as mining brings radioactive elements into the surface.  Therefore, phophate mining increases outdoor radon levels However, this increase does not cause any significant threat to human health as radon gas quickly disseminate in the atmosphere into undetectable concentrations. (FIPR,2018).  Dust can be generated from almost all mining activities including crushing phophate rock, product storage, transportation of ore, phosphogypsum stacks (Chernaik et al., 2010). Dust may also contain of radioactive particles. However, the use of wet process has significantly lowered the amount of dust emitted to the environment while dust produced from processing and product storage has greatly reduced since 1980’s with the use of oil coating its products (FIPR.2018).

 

Impacts on human health

About 57 trace elements in phophate rocks have been identified to contain various levels of toxicity. Out of those 57 elements, Be, As, Cd, Hg and Ra are recognized as extremely toxic (Chen., 2015). Following table illustrates the degree of toxicity of various elements found in phophate rock.

Associated elements found in phophate rock

 

Degree of toxicity

Be, As, Cd, Hg, Tl, Ra

F, Cl (Cl2), Cr, Ba, Gd, Yb, Pb

Li, Ni, Cu, Ga, Sn, Sb, Te, La, Ce, Pr, Nd, Sm, Tb, Ho, Bi, Th, U

Ca, V, Mn, Fe, Zn, Ge, Mo, Lu

Mg, S, Ca, Sc, Co, Se, Sr, Y, Zr, Nb, Ag, In, I, Dy, Eu, Er, Tm, Hf, Au

Extreme

High

Moderate

Low

Negligible

Data Source: Reta (2018)

More than 21000 lung cancer deaths per year in United States are associated with radon gas. Decay products of radon gas can enhance lung cancers by destroying cells in the lung tissues. In Florida, one in 5 homes tested have been identified to exceed the EPA permissible radon levels of 4pCi/L. Since radon is a gas contain in soil, it can enter a building through flooring. Once it is entered to a building, it can trap and build up on closed buildings into a higher concentration than outside air. Since radon is colorless and odorless gas, there is no way to identify it rather than testing (“Florida Health”,2018). According to the EPA radon zones map, none of the Florida counties have a predicted average indoor radon screening level greater than EPA standard concentration of 4 pCi/L. However, few counties in North, Central and South East Florida have a moderate radon potential which contains radon screening level between 2 and 4pCi/L. Most of the other counties indoor radon levels are below 2pCi/L.

Data Source: Map of Radon Zones in Florida based on EPA data.

Impacts on land/soil and Biodiversity

As Florida phophate mining is a surface or strip-mining process which can impact large surface area of the land causing more environmental damage compared to underground mining (Dudka,1997). During the exploration, land can be disturbed in variety of ways including removal of vegetation, building camps and access roads, drilling activities. Clearing of vegetation may have impact on local hydrological cycle, habitats of variety of species, thus reducing the biodiversity in the area. Construction activities may have more impact on land through earth works. During extraction, land and soil gets further disturbed by the removal of vegetation and top soil, extraction of large quantity of earth, depositing overburden, building waste dumping areas and clay settling ponds (UNEP,2001).

Conclusion

Environmental impacts of phophate mining were far wide to be covered in this review. However, I was able to address the impacts on water resources, air quality and human health. Several studied have been conducted to assess the impacts of phophate mining and processing on Water resources in Florida.  Based on those studies, it can be concluded that phophate mining has a significant impact on water resources. According to those studies phophate mining affects the local hydrology of the area by utilizing large quantity of water. It also changes the landscape of the areas which eventually affects the natural flow patterns. Few other studies conducted to assess the impacts of phophate mining on water quality have suggested that discharges of acid mine water into local waterways change the water quality. Those studied have mostly concerned about the discharge of acid mine water into surrounding wetlands and streams, release of radioactive and toxic metals into the environment. Air quality was affected mainly by Fluoride and radon gas emission. Dust was a common issue as it was produced throughout all the mining activities. Human health can be impacted mostly by toxic metals and radioactive elements as phophate products were mainly composed of Pb, Cd, Cr, As, U and Ra.

References:

  • (Breeze, 2002)
  • Riggs (1979)
  • (Riggs, 1979, Van Kauwenbergh et al., 1990).
  • (Lane, 1994).
  • al Rawashde and Maxwell, 2011).
  • (Jasinski, 2011).  
  • M. Chen, T.E. Graedel, The potential for mining trace elements from phosphate rock. Journal of Cleaner Production. 2015; 91:337‒346.
  • UNEP, Environmental aspects of phosphate and potash mining, First Edition, Association IFI, UNEP,Paris, 2001;1‒68.
  • T.M. Cioroianu, F. Bunus, D. Filip and G. Filip, Environmental considerations on uranium and radium from phosphate fertilizers: Impact of new environmental and safety regulations on uranium exploration, mining, milling and management of its waste, 215 (No. IAEA-TECDOC–1244).2001
  • UNEP, Environmental Aspects of Phosphate and Potash Mining. First edition. Printed by UNEP and IFA, Paris, 2001. UNITED NATIONS PUBLICATION ISBN:92-807-2052-X
  • J. Polk, Persoiu, Aurel, J. P. -Graczyk and Kali. (2007). Underground Florida: A fieldtrip guidebook of the West Central Florida karst.
  • S. Dudka , D.C. Adriano, Environmental impacts of metal ore mining and processing: a review. Journal of environmental quality. 1997;26(3):590‒602.
  • C. Beavers C, R. Ellis, C.D.E. Hanlon CDE and G. MacDonald, An overview of phosphate mining and reclamation in Florida. Citeseer. 2013;1‒33.
  • M. Wilson and E.A. Hanlon Landscape Diversity: Florida Phosphate Mine Pit Lakes; U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension, (2012).
  • B. Lewelling, R. Wylie.  Hydrology and water quality of unmined and reclaimed basins in phosphate-mining areas, west-central Florida. US Geological Survey. 1993:1‒102.
  • D.P. Foley, and A.L. Pollock, Evaluation of the effectiveness of neutralizing accidental spills of acidic waste water from holding ponds.  FIPR Publication No.  01-155-160. (2000).
  • J.A. Miller, G. Hughes, R. Hull, et al. (1978). Impact of potential phosphate mining on the hydrology of Osceola National Forest, Florida. US Geological Survey, Water Resources Division. P:1‒174.
  • PBS&J (2007), Peace River Cumulative. Impacts Study Summary. 2007;107
  • R.L. Miller and H. (Fine P) Sutcliffe, Effects of three phosphate industrial sites on ground-water quality in central Florida, 1979 to 1980. US Department of the Interior, US Geological Survey. 1984;1‒194.
  • D.A. Manning, Phosphate minerals, environmental pollution and sustainable agriculture. Elements. 2008;4(2):105‒108.
  • L. Toler, Fluoride in water in the Alafia and Peace River basins Florida. Florida Geological Survey Report of Investigations. 1967; 46:1‒54.
  • K.J. Jardin, W. N. Futch, and D. H. Michalski, Piney Point Pond Water Remediation Using Reverse Osmosis.  FIPR Publication No. 01-183-214 (2005).
  • EPA, EPA Basic Radon Facts, EPA 402/F-16/002 | July 2016
  • M. Chernaik, Guidebook for evaluating mining project EIAs. Environmental Law Alliance Worldwide 8. 2010;1‒122.
  • G. Reta, X. Dong, Li, Zhonghua, et al. Environmental impact of phosphate mining and beneficiation: review. Int J Hydro. 2018;2(4):424‒431. DOI: 10.15406/ijh.2018.02.00106
  • EPA, EPA Assessment of Risks from Radon in Homes, EPA 402-R-03-003 , Environmental Protection (6608J) June 2003 or 2013
  • C. Szilas, The Tanzanian Minjingu phosphate rock. Possibilities and limitations for direct application. Center for Skov, Landskab og Planlægning/Københavns Universitet. 2002;1‒187.

Cite This Work

To export a reference to this article please select a referencing stye below:

Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.

DMCA / Removal Request

If you are the original writer of this essay and no longer wish to have your work published on the UKDiss.com website then please: