Beneficiation Studies of the Low-Grade Skarn Phosphate from Mactung Tungsten Deposit, Yukon, Canada

A preliminary beneficiation study of low-grade skarn phosphate rocks from Mactung tungsten deposit, along the Yukon and Northwest Territories border in Canada, was carried out through standard Bond Work Index, grinding test and laboratory batch flotation tests. The skarn phosphate sample assayed 12.65% P2O5 (about 30% apatite), 31.71% CaO and 35.46% SiO2. The main gangue minerals included calcite, quartz, calc-silicates, amphibole, feldspar, and pyrrhotite. The sample had a Bond Work Index of 19.04 kWh/t, belonging to a hard ore category. The beneficiation study of the skarn phosphate sample was carried out using “direct–reverse flotation” method. The direct flotation was carried out using sodium carbonate, sodium silicate solution (water glass) and sodium oleate. Sulfuric acid and phosphoric acid were used in the reverse flotation of the carbonate gangue. One phosphorous rougher flotation, one bulk cleaner flotation and one carbonate reverse flotation at ore grind size of 86% passing 53 µm led to a phosphate concentrate assaying 28.68% P2O5, 12.06% SiO2, 0.72% MgO and 46.98% CaO, at a P2O5 recovery of 70.9%.

Production of a Phosphate Concentrate from the Tailings of a Niobium Ore Concentrator

Apatite is the main source of phosphorous for the making of chemical fertilizers. While apatite is usually recovered from phosphate orebodies as the primary product of a mining exploitation, this paper documents the approach taken to produce a phosphate concentrate as a secondary product from the tailings of a niobium ore concentrator. The conventional desliming/flotation scheme used to process phosphate ores was tested and adapted to process one of the reject streams of a niobium concentrator in order to produce a salable phosphate concentrate. For that particular material, it was found that the reverse flotation of apatite yielded better results than the commonly used direct flotation of apatite. The recommended approach to produce the phosphate concentrate is desliming followed by reverse flotation of apatite and an acid leaching of the apatite concentrate to lower the MgO content below the specification for a phosphate concentrate. The obtained phosphate concentrate assays more than 32% P2O5 at a P2O5 recovery of 41%, which although low is found to be economic for the case of processing plant reject tailings.

Flotation Studies on Low-Grade Phosphate Rock of Tarnawai, District Abbottabad, KPK Province, Pakistan

A low-grade siliceous sedimentary phosphate rock assaying 22.05% P205 was upgraded by double float (direct and reverse) technology. The rock contains collophane (carbonate fluorapatite) as the valuable phosphate mineral along with siliceous, carbonaceous and clay minerals. A process was developed which yielded a high-grade phosphate concentrate with improved recovery rate. The developed process consists of three parts. The first part includes wet grinding of ore to liberation point followed by separation of fines (slimes) by cone classifier. The finely ground deslimed ore was floated by direct anionic flotation using oleic acid collector to get rougher phosphate concentrate. It was cleaned once using additional quantity of reagents. In the second part, the fines generated during grinding operation were floated by column flotation to recover phosphate values. The cleaned concentrate and column concentrate were mixed together and washed thoroughly with hot water to remove the attached reagents. The final part comprises of cationic flotation of combined phosphate concentrate with fatty amine collector to float away quartz and silicates and to leave behind phosphate values. The grade of final phosphate concentrate was found to be 32.85% P205 with an overall recovery of 88.14%. The concentrate obtained meets the specifications of fertilizer and acid grade.

Review on Beneficiation Techniques and Reagents Used for Phosphate Ores

Phosphate ore is an important raw material for manufacturing fertilizers and phosphorous chemical products. While most of the phosphate resources cannot be directly treated as feed stock due to the low grade of P2O5 and high content of impurities. In order to obtain a qualified phosphate concentrate, the beneficiation of the low-grade phosphate ore is, hence, of great necessity. Many beneficiation techniques can be employed to upgrade the P2O5 grade of phosphate ores based on their characteristics in chemical composition and texture. The flotation process is most widely applied to balance the P2O5 recovery ratio and cost. In this review, the dominant techniques for the beneficiation of phosphate ores are introduced. Moreover, the factors that affect the flotation of phosphate ore, including the properties of mineralogy, flotation reagents (depressants and collectors) and flotation medium, were systematically analyzed.