Phosphate rock resources

Northolt, A. J. G., Shelton, R. P, and Davidson, D. F., Phosphate Deposits of the World, Vol. 1, Phosphate Rock Resources, Cambridge University Press, 1990. 

Nitric Phosphate. About 15% of worldwide phosphate fertilizer production is by processes that are based on solubilization of phosphate rock with nitric acid iastead of sulfuric or phosphoric acids (64). These processes, known collectively as nitric phosphate or nitrophosphate processes are important, mainly because of the iadependence from sulfur as a raw material and because of the freedom from the environmental problem of gypsum disposal that accompanies phosphoric acid-based processes. These two characteristics are expected to promote eventual iacrease ia the use of nitric phosphate processes, as sulfur resources diminish and/or environmental restrictions are tightened. 

Table 14. World Reserves and Resources of Phosphate Rock ...

At the present rate of world phosphate rock consumption (150 x 10 t/yr), the total world reserve (Table 14) is sufficient for about 200 years, and the resource would be sufficient for nearly 900 years. At expected increased rates of consumption, the reserves and resources are adequate for at least 150 years and 700 years, respectively. At projected rates of consumption, the high grade reserves in Florida probably will be exhausted by the year 2000. Rock production from the Florida reserve presentiy constitutes about 80% of all United States production and about one-third of world production (106). This rate of depletion is causing increased interest in western United States reserves which represent nearly 80% of present U.S. total reserves. 

Resources of Sulfur. In most of the technologies employed to convert phosphate rock to phosphate fertilizer, sulfur, in the form of sulfuric acid, is vital. Treatment of rock with sulfuric acid is the procedure for producing ordinary superphosphate fertilizer, and treatment of rock using a higher proportion of sulfuric acid is the first step in the production of phosphoric acid, a production intermediate for most other phosphate fertilizers. Over 1.8 tons of sulfur is consumed by the world fertilizer industry for each ton of fertilizer phosphoms produced, ie, 0.8 t of sulfur for each ton of total 13.7 X 10 t of sulfur consumed in the United States for all purposes in 1991, 60% was for the production of phosphate fertilizers (109). Worldwide the percentage was probably even higher. 

Calcium. Calcium is the fifth most abundant element in the earth s cmst. There is no foreseeable lack of this resource as it is virtually unlimited. Primary sources of calcium are lime materials and gypsum, generally classified as soil amendments (see Calcium compounds). Among the more important calcium amendments are blast furnace slag, calcitic limestone, gypsum, hydrated lime, and precipitated lime. Fertilizers that carry calcium are calcium cyanamide, calcium nitrate, phosphate rock, and superphosphates. In addition, there are several organic carriers of calcium. Calcium is widely distributed in nature as calcium carbonate, chalk, marble, gypsum, fluorspar, phosphate rock, and other rocks and minerals. 

In the geochemistry of fluorine, the close match in the ionic radii of fluoride (0.136 nm), hydroxide (0.140 nm), and oxide ion (0.140 nm) allows a sequential replacement of oxygen by fluorine in a wide variety of minerals. This accounts for the wide dissemination of the element in nature. The ready formation of volatile silicon tetrafluoride, the pyrohydrolysis of fluorides to hydrogen fluoride, and the low solubility of calcium fluoride and of calcium fluorophosphates, have provided a geochemical cycle in which fluorine may be stripped from solution by limestone and by apatite to form the deposits of fluorspar and of phosphate rock (fluoroapatite [1306-01 -0]) approximately CaF2 3Ca2(P0 2 which ate the world s main resources of fluorine (1). 

The estimated world resources of Zr were published in 1968 (Ref 13). The United States is believed to have the largest reserves of Zr in the world, as shown in Table 2. But the recovery of Zr from domestic sources is economically feasible only as a byproduct of the Ti manufacture. Large quantities of zircon are obtainable through the mining and processing of phosphate rock. Commercial recovery of Zr from these sources is subject to the economics or Zr utilization... 

Herring, J. R., and Fantel, J. R., Phosphate Rock Demand into the Next Century Impact on World Food Supply, Nonrenewable Resources, 2(3), 226-241 (1993). 

Smface minir is less expensive and safer than tm-dergromrd mining. About 90% of the rock and mineral resources mined in the United States and more than 60% of the nation s coal is produced by surface minir techniques. Coal mining accomrts for abotrt half of all sitr-face mining, extraction of sand, gravel, stone, and clay for another 35%, phosphate rock for about 5%, and all metallic ores, for abotrt 13%. 

S.M. Jasinsky, Phosphate Rock 2001. In Minerals Yearbook. US Geol. Survey. Available http //minerals.usgs.gOv/minerals/pubs/commodity/phosphate rock/index.html myb Phosphate, Miner. Bull. MR 160. Energy Mines and Resources Canada, Ottawa, 1976. 

In planning resource-based industries in remote regions, where transport of low-value byproducts can be costly. An important case in Australia is sulfur dioxide emissions capture from metallurgical smelters to make sulfuric acid. Sulfuric acid can be used for phosphate fertilizer manufacture, but depends on availability of phosphate rock deposit, natural gas supply (for ammonia production), and infrastructure for transporting the fertilizer to markets. 

Although fertilizer production has decreased drastically in recent years, these markets, especially Eurasia, are rich in raw materials such as natural gas, potash ores, and phosphate rock. Therefore, they will continue to play an important role in supplying nitrogen and potash fertilizers in the global markets. Because Eastern Europe is not as rich in energy resources and raw materials, increased energy costs may reduce its comparative advantage in world fertilizer markets. 

World Phosphate Rock Reserves and Resources. Resource/reserve data for specific raw materials are presented in each section. 

The United States and other countries wiD not, however, simply run out of phosphate rock at some predetermined date in the future. Table 5.18 indicates the amount of phosphate reserves available from various mining areas in the United States in terms of cost per tonne. Most of the current reserve figures assume a maximum cost of 40/tonne for estimates. If the cost of phosphate rock reaches 60/tonne, the U.S. reserve base more than doubles to 2.8 x 10 tonnes. These types of detailed data are not available for most other world producers although Fantel, Peterson, and Stowasser 1621 have estimated the amounts of poten-tiafly recoverable phosphate rock at various production costs from all deposits in market economy countries, the United States, North Africa, and the Middle East. It is reasonable to assume that a similar situation governs the reserve/resource situation in other countries around the world. If phosphate rock prices eventually rise worldwide, a portion of the phosphate rock now classified as resources in many countries will be reclassified as reserves. 

Fhosphate rock prices will increase when demand approaches the limits of supply. When phosphate rock prices increase, some resources become rieserves, marginal mining projects become xtoble, and production is stimulated. In the future, fuel and kiel-related transportation costs may become even more important components in the world phosphate rock production scenario. Political disruptions, always an unknown factor, can profoundly influence the supply and demand for fertilizer raw materials on a worldwide basis. 

The main purpose of the latter policy is to enable much less costly sources of phosphate rock to be brought into use. This plays an important role in countries with large reserves of phosphate rock, but with inadequate finandal resources to invest in industrial production of phosphoric acid, TSP, and ammonium phosphates. 

The estimated value of domestic (nonfuel) mineral raw materials mined in the United States is 40 biUion (net imports into the United States amount to 29 billion) Nine of these minerals have an annual production value of over 1 billion at the present time. These are mainly commodity construction materials such as sand and gravel but also include key metals such as gold, copper, iron, as well as phosphate rock. For some important minerals the United States depends entirely on exports and conscientious exploitation of the ore resources in foreign countries will be crucial to domestic economic development. Ores of precious and rare-earth metals, for instance, cannot be replenished in a practical time scale and their applications typically do not allow these to be recycled effectively. An energy-rich material-poor world is as bleak a prospect as one with no future energy options. 

Enrope (EEC) remains the largest importer of phosphate but is now a negligible producer. India, the second largest importer, is increasing phosphate rock production, but much of the rest of Asia, with the exception of China, appears to have insufficient resources to meet its requironents now or in the foreseeable future. China continues to expand production, which in 2007 surpassed that of the United States for the first time. 

Reliable figures for many phosphate rock reserves are difficult to obtain since conflicting data have been published and estimates are continually being revised. Reserves are considered by most authorities to be that part of the known resources which can be at present profitably recovered. Revision will be necessary whenever new deposits are discovered or if significant advances are made in technology. If only present economically workable deposits are considered, Moroccan (and Western Sahara) reserves (20,000-50,000 million tons) exceed the combined resources of the United States, Russia and China. Other estimates (2009) have put world reserves at -18,000 million tons, of which China and Morocco probably hold about 1/3 each. South Africa and the United States around 6-8% each and Australia about 1%. 

Phosphorus is an essential element for plant and animal nutrition and phosphate rock is the only signihcant resource of phosphorus [9]. Phosphate rock is converted into phosphoric acid, which in turn is converted into phosphorus fertilizers. Common examples of phosphorous-containing fertilizers are triple superphosphate, monoammonium phosphate, diammonium... 

The best known (sometimes infamous) method of surface mining is strip mining, in which strips of overburden are removed by draglines and other heavy earth-moving equipment to expose seams of coal, phosphate rock, or other materials. Heavy equipment is used to remove a strip of overburden, and the exposed mineral resource is removed and hauled away. Overburden from a parallel strip is then removed and placed over the previously mined strip, and the procedure is repeated numerous times. Older practices left the replaced overburden as relatively steep erosion-prone banks. On highly sloping terrain, overburden is removed on progres-... 

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