Iraqi Bulletin of Geology and Mining

Phosphate rocks are the commercial source used as raw material for manufacturing phosphoric acid, phosphate fertilizers and certain other chemicals. Phosphate rocks can be used directly in some applications, whereas beneficiation is required to upgrade the ore to more than 29% of P2O5 when used as a raw material for the production of fertilizers, phosphoric acid and many other phosphate compounds. Phosphatic fertilizers are the most important end-product of phosphoric acid. Production of phosphoric acid is the first step in the manufacture of many phosphatic fertilizers. Phosphoric acid and phosphate compounds can be used directly in chemical industries or as a key ingredient in the production of many other chemicals required in detergents, animal feed, food, beverages, surface treatment (metal cleaning, coating), water treatment, dentistry, tooth pastes, fire extinguishers amongst many others. High purity phosphate compounds are also used in food and pharmaceutical production. Phosphorus as an element and some other phosphoric chemicals derived from phosphate rocks are used in pesticides, matches, fireworks and also in many military applications.

Phosphorite deposits of Late Cretaceous and Paleogene age are well known in the Iraqi Western Desert. They are part of the regional phosphorite belt of the Tethys which is best developed in North Africa and East Mediterranean countries and is considered to include the largest marine upwelling-type deposits in the world.
The phosphorites of Iraq, as with the other deposits of this belt, are marine sedimentary stratiform deposits, granular in texture, associated with limestone, shale, chert and occasionally sandstone. The phosphorite beds may reach several meters in thickness, and show common features of hardgrounds and bioturbation. Silicification is common in these deposits. They were deposited in several cycles of phosphogenesis, extended from Maastrichtian to Middle Eocene. Most of the Iraqi phosphorite deposits, except those in the Nukhaib area, were laid down west of the Horan High, in successive episodes, culminated in the Paleocene.

The phosphate components consist mostly of coated grains (cortoids and ooids), uncoated grains (peloids) and to a lesser extent phosphoclasts (mostly bones) and coprolites. The cementing material is commonly calcite; occasionally silicified. The only phosphate mineral identified is francolite. The P2O5 content of the Iraqi deposits is generally in the range of (18 – 25) %, but typically (20 – 22) %; the main diluent is calcite cement. The phosphorites, as with most upwelling marine deposits, are relatively enriched in F, U, Cd, Sr, Y and REE, which are associated with the phosphate phase.
The indicated phosphate resources of Iraq were estimated by about 10 billion metric tones, which put Iraq the second after Morocco in that respect. These resources are divided among several deposits; most of which are bordering the northern and western rims of the Ga'ara Depression. They are: Akashat, Swab, Hirri, Marbat, Dwaima, H3 and Ethna. The bulk of the phosphate resources is found in the Paleocene Akashat Formation. The H3 deposit includes parts of the Late Cretaceous sequence (Digma Formation), whereas the Ethna deposit is merely of Middle Eocene age (Ratga Formation). Among the Iraqi deposits, only Akashat has been developed and exploited since the early eighties of the past century.

This article is meant to cover the general aspects of mining and beneficiation of the Iraqi phosphate rocks. The phosphate deposits in Iraq extend over the Western Desert in Al Anbar Governorate. The Akashat mine, located about 500 Km west of Baghdad, is the first phosphate mine opened in Iraq and has been operating since 1983. The average content of P2O5 is about 20%. The tailings constituents are mainly carbonates, silica, and clays. The phosphate ore is mined by open cast mining in two quarries. The mined rock is transported to Al-Qaim fertilizer complex by train where upgrading is carried out in the beneficiation plant through different operations including crushing, homogenization, calcination, slaking, washing and desliming. The beneficiated phosphate rocks, with 29 – 30 % P2O5 content, are used for the production of phosphoric acid and phosphatic fertilizers.

Iraq has been producing phosphate since 1983 from the Akashat mine. Mining is being carried out by open cast strip mining method due to the stratiform nature of the phosphate beds and low stripping ratio. Phosphate beneficiation is carried out at the phosphate beneficiation Plant at Al-Qaim Fertilizer Complex to raise the content of P2O5 from 19 – 20 % to about 30% through the calcination process. Recent study has been carried out to beneficiate Akashat phosphate by froth floatation techniques, the results indicated the possibility of increasing the content P2O5 to the levels required for the fertilizer industry and other industrial uses. The massive discoveries of phosphate rock reserves in the Western Desert indicate that the deposit has a high variable stripping ratios and different content of P2O5 as well as different levels and contents of associated gangue minerals and compounds. Accordingly it became necessary to outline some of the mining problems and the best methods of beneficiation techniques in which the phosphate components can be increased. The results obtained in the research conducted on samples of phosphate rock from unexploited phosphate in the Western Desert showed the possibility of increasing the content of P2O5 up to 30% using the traditional calcination method and some deposits need only simple beneficiation processes.

Phosphate rocks that have been discovered in Akashat area/ Anbar Governorate, provided the basis to establish the phosphate fertilizers industry in Iraq. The State Company for Phosphate was established for the investment and management of phosphate rocks in Akashat mine and fertilizer complex in Al-Qaim. The company’s products (including intermediate products) include sulfuric acid, phosphoric acid, and phosphate fertilizers such as TSP (Triple Super Phosphate), MAP (Mono-Ammonium Phosphate), and the compound fertilizers (NP and NPK). Production in the company began in 1983, but has faced many problems, especially since 1991. During this period, the production rate was not at the required level. Now Akashat mine and Al-Qaim fertilizers complex require complete rehabilitation in order to get the phosphate fertilizer production level back to its designed capacity.

Trials have been attempted to evaluate the recovery of some trace elements in the Iraqi phosphate rocks and phosphate fertilizers products since the nineties of the twentieth century. Leaching solid-liquid extraction was conducted for the recovery of Cd and Zn from the basic slime wastes produced in the Iraqi Al-Qaim fertilizer complex using various inorganic acids, basis and ammonium salts. Almost quantitative recovery was obtained for Cd and Zn by ammonium chloride and ammonium nitrate solutions.
A method has been developed for the recovery of U, Th and other heavy elements from the acidic phosphogypsum produced as waste at Al-Qaim fertilizer complex using the concept of preferential solubility of phosphogypsum over other trace elements sulfates and phosphates in potable water. The undissolved or partially dissolved metal salts remain hanged as colloids then accumulated after 30 – 60 minutes. Most of the trace elements are expected to exist in water as sparingly or insoluble sulfates, phosphates, silicates and fluorides. Chemical analysis of the isolated phosphogypsum, after water evaporation, showed reasonable purity suitable for various industrial applications. The method has been further developed recently using pH, conductimetric and turbidometric techniques to follow the solubility of phosphogypsum as function of various parameters.
Uranium, on the other hand, was recovered on industrial scale, from green phosphoric acid by liquid-liquid extraction technique and di-2-ethyl-hexyl-phosphoric acid (DEPA)-trioctylphosphene oxide (TOPO)-kerosene/ phosphoric acid solutions. The plant installed at Al-Qaim depends on mixer settlers as contactors. More than 150 tons of uranium was recovered as yellow cake, but the plant was destroyed during the 1991 war. High purity phosphoric acid was produced from green phosphoric acid on a pilot plant scale using liquid-liquid extraction technique and mixer-settler contactors. The extraction system "40% tributyl phosphate (TBP)-kerosene" was applied as the organic phase. The process revealed group removal of U, Th and other heavy metals as by-products in 20% green phosphoric acid.

Unfortunately phosphate rock mining and fertilizer industry manufacturing operations are not environment friendly. It releases huge amount of toxic contaminants into air, water and soil, which led this industry to cause serious environmental problems, among which, fluorides and radionuclides the primary toxic pollutants. This brief review highlights many issues of environmental concern; among which are the impact of natural radionuclides present in phosphate ores, and along the processes, waste products, and radon emanation problems. Phosphate fertilizers contaminate agricultural soils with radionuclides and heavy metals through regular application, in such a way that it necessitates their removal from the end products. The cost of extraction of uranium from phosphoric acid as byproduct compensates much of the cost of purifying the acid. The environmental impact and the improved waste management requirements include harmful gas rendering, controlling effluent waste below harmful levels, as well as the proper dumping of the huge amount of phosphogypsum waste. Recent waste management procedure and general guidelines to mitigate or reduce the environmentally harmful impacts of the contaminant are given in this review.

The extensive geological and mineral exploration works in Iraq revealed large resources of potentially economic marine sedimentary phosphate deposits in the Western Desert. The indicated resources are estimated by about 10 billion tons, whereas the reserves are over 5 billion tons of phosphate rocks with 20 – 22 % P2O5 content. Phosphate mining has started by the Iraqi government in the Akashat deposit in the early eighties of the past century with a designed capacity of 3.4 Mt/year to feed the fertilizers plant at Al-Qaim, designed to produce 1 Mt of fertilizers/year. Since 1991, the development of phosphate industry in Iraq faced serious problems which hindered the commissioning of new mines and expanding fertilizers production. Moreover, mining in Akashat and fertilizers production at Al-Qaim have almost stopped after 2003. The availability of large phosphate reserves with suitable specifications and feasible mining and beneficiation conditions call for immediate measures to start new mining projects and fertilizers production plants, as well as rehabilitation of the available facilities, to be implemented by partnership of the government with the private sector. Modern technologies should be introduced to ensure best practices in mining, beneficiation and fertilizers industry, in addition to maintaining safe and clean environmental conditions. Guidelines for future development of phosphate industry in Iraq are presented in this paper including potential deposits for exploitation, conditions for licensing, requirements of the new projects, production capacities, products and by-products, environmental protection and economic impact.