| As main raw materials for iron and steel industry, the iron ore is an important resource for national strategy. Although the total reserve of iron mine resource in China is abundant, much of it which have been detected is poor and less rich. Therefore, a considerable amount of iron raw materials is still bought from abroad.The content of the iron ore with high phosphorus is about 15% among the total iron ore which have been proven. It is of great importance that how to utilize the high phosphorus iron ore by effectively removal of phosphorus.The iron ore is from a iron mine in DongChuan, in which iron is the main elment. Its main valuable minerals are hematite. Whereas quartz and calcite are main gaugue minerals. The phosphorus in the iron ore mainly exists in the form of colloidal phosphorite. Partial phosphorus is exists in the limonite with the form of isomorphism. And iron colloidal phosphorite fills in hematite. Furthermore there is few phosphorus exists in main gangue minerals as quartz.The run-of-mine is taken from five mines basing on charactaristic of each one. These five ores are proportionally matched to the run-of-mine. The matched run-of-mine contains 43.75% Fe and 0.39% P. A iron concentrate which contains 60.49% Fe and 0.31% P with yield of 41.07% at a recovery of 56.78% is obtained with one rougher and one cleaner by high-gradient magnetic separation. Taillings from the cleaner still has 43.46% Fe. While the taillings from the rougher is further scavenged to produce aonther concentrate which contains 44.96% Fe. These two mentioned products are delivered to secondary grinding together, then dealt with by high-intensity magnetic separation and cleaned by shaking table. The iron concentrate producted from shaking table has a yield of 44.96% and contains 57.60% Fe and 0.33% P at a recovery of 6.61%. The middlings from the shaking table has a yield of 6.54% and contains 51.43% Fe and 0.37% P at a recovery of 7.71%. So a final iron concentrate (the concentrate cleaned from the high-gradient magnetic separation and the concentrate cleaned from the shaking table) contains 60.18% Fe and 0.32% P with the yield of 46.08% at a recovery of 63.39%. Obviously the iron concentrate contains much element of phosphorus. In order to enhance the quality of the iron concentrate, the removal of phosphorus is acheived by appling reverse-flotation to treat mixed minerals of iron concentrates and middlings (cleaned from the shaking table). The mixed minerals contain 59.17% Fe and 0.32%P at a recovery of 71.10%. Through a lists of reagent expriments, at last, it is determined that the slurry is regulated at PH 11 with NaOH and Na2CO3, the depressant is caustic starch+AX-1+AX-2 with the usage of 1200g/t, and the collector is oleic acid+ coal oil +BX-1 with the usage of 225g/t. This reagent scheme is applied to treat mixed minerals, and finally the iron concentrate contains 62.86% Fe and 0.24% P with a yield of 41.33% at the recovery of 59.33%, discreasing the phosphorus element and enhancing the grade of iron concentrate.The reaction mechanism of each reagents have been studied here. The main composition of regulator Na2CO3 is CO32- when the slurry PH is 11. The depressant can adsorb on the mineral surface by its polar group and hydrophilic colloid formed in solution, rendering certain minerals hrdrophilic to be depressed. The collector fixes on the mineral surface by the combined functon of physical adsorption and chemical adsorption, forming hydrophobic polymer and redering the minerals hydrophobic to be floated. |
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