Study On Reagent And Process For Reverse Flotation Desilication Of Medium And Low Grade Silica-Magnesium Collophane

Phosphate rock,as a non-renewable resource,is an important component of agricultural fertilizers and phosphorus-based chemicals.As the second largest phosphate rock resource country in the world,China has a total resource of 857 million tons.In the recent years,with the continuous exploitation and utilization of phosphate rock resources,the properties of ore gradually approach to the status of poor grade,fine dissemination and complex composition,which makes this kind of ore more difficult to upgrade.Therefore,the research on beneficiation technology of collophane is of great significance for the rational development and utilization of phosphate rock resources in China.The proven reserves of collophane account for 80%of the total of phosphate reserve,most of which are medium and low grade collophane.This kind of collophane is characterized by low grade,complex structure,fine dissemination grain size and difficult dissociation.For the medium and low-grade collophane containing both carbonate and silicate minerals,the double-reverse flotation process is mainly adopted.However,desilication collectors for reverse flotation still have some disadvantages,such as being only suitable for weakly alkaline conditions,and being difficult to defoam.So efficient reverse flotation collectors for separating collophane with medium and low grade,high silicon and high magnesium need to be developed urgently.This paper is based on the AMICS mineralogical analysis of collophane flotation feed with medium and low grade,silicon and magnesium in a certain area of Yunnan.A novel cationic collector KDJ was identified for reverse flotation of collophane for silicon removal through pure mineral flotation test of quartz and collophane.Secondly,KDJ was used as collector for silicon removal,and parametric tests,optimization test,open circuit test and closed circuit test were carried out through the double reverse flotation process.Finally,the flotation mechanism was studied in depth by means of sieve analyses,infrared spectroscopy and contact angle tests.The results of AMICS analysis of flotation feed show that the phosphorus in the sample mainly exists in the form of fluorapatite and the gangue minerals are primarily dolomite and quartz.Fluorapatite has a fine dissemination particle size and is mainly distributed over a particle size range of 10～75μm with a degree of mineral liberation of 59.17%.In addition to its existence in the form of liberated particles,fluorapatite is mainly associated with dolomite and quartz with their composite particle content of26.23%and 9.92%,respectively.The result shows that under the conditions of p H 6and collector KDJ dosage of 25 mg/L,the pure quartz sample showed a recovery of97.83%while pure collophane sample exhibited no recovery.In the flotation test of binary artificial mixture of pure collophane and quartz,the collophane concentrate showed a P₂O₅ recovery of 71.88%and no quartz recovery at p H 6 and a collector KDJ dosage of 150 mg/L.The actual mineral flotation test shows that a closed-circuit flotation process of magnesium removal with rougher and desilication with one rougher and two scavengers obtained a good performance of 82.74%P₂O₅ recovery,29.62%P₂O₅ grade and 12.71%Si O₂ in the concentrate under the optimal conditions of p H 5.84for magnesium removal,a sodium hexametaphosphate dosage of 2.71 kg/t,a saponified fatty acid dosage of 0.87 kg/t,p H 6.0 for desilication,a KDJ dosage of 0.4 kg/t.In combination with the mineralogical analysis results,it was suggested that the main reasons for the difficulty in obtaining better performance are the fine particle dissemination size of collophanite,the difficulty in obtaining a better degree of mineral liberation,and the serious slime generation.The results of infrared spectrum analysis show that the adsorption mode between collector KDJ and actual minerals is physical adsorption.And the contact angle test results show that KDJ can significantly enhance the hydrophobicity difference between quartz and collophane and improve the flotation effect compared with the traditional collector for desilication of collophane.Collector KDJ for effective reverse flotation of collophane for silicon removal has been developed that can be suitable for acidic pulp condition.