Experimental Study On Flotation Of Yichang Mid-low-grade Potassium-containing Phosphate Ore

As nutrient elements fertilizer for crops, phosphate and potash fertilizer play a crucial role in the process of crop metabolism. Constrained by resources, the phenomenon that having excess nitrogen while lacking phosphorus and potassium is very serious in our country’s chemical fertilizer industry, which greatly limits the development of agriculture in our country. Since most of our phosphorite is mid-low-grade and paragenetic ore, the development of the phosphate and potash fertilizer industry is greatly impeded due to some big technical issues.Developing our rich reserves of mid-low-grade phosphate and insoluble potassium resource vigorously is the necessary way for the sustainable development of our country’s chemical fertilizer industry. Yichang area is rich in potassium-containing phosphate ore, which has the natural symbiotic characteristics of phosphate and potassium. Compared to the single use of phosphate or potassium, the comprehensive use of phosphorus and potassium in the potassium-contaning phosphate ore has more economic advantages. Developing the potassium-containing phosphate ore economically and rationally has an important guiding significance to our country’s comprehensive utilization of potassium-containing phosphate ore.In this work, the characteristics of the mid-low-grade potassium-containing phosphate ore in Yichang area, including the mineral components, morphology, grain size and mineral dissemination, were firstly studied and then flotation of the ore was carried out based on the characteristics of the ore. The main conclusions are as follows.（1） The main valuable minerals in mid-low-grade of potassium-containing phosphate ore are cellophane and potash feldspar, while the gangue minerals are quartz, dolomite and pyrite. The mass fractions of P2O5 and K₂ O in the ore are 20.92% and 4.59%, respectively. The collophane ore is cryptocrystalline aggregates, which present a laminar structure. The feldspar with an irregular granular structure partly presents a tabular crystal morphology while mostly generates sericite presenting a fine flake structure. The quartz is irregular granular structure, which presents scattered distribution.（2） Under the parameters of grinding fineness-0.074 mm 93.64 %, sodium carbonate 6 kg/t, sodium silicate 3 kg/t, TSM-46 1.8 kg/t, flotation time 5 min, and flotation temperature 20±1 ℃, the grade of P2O5 increases from 20.92 % to 27.72 %, after one roughing process. Through one featured and one scavenging process to further enrich phosphate and feldspar, the grade of P2O5 in concentrate reaches 31.84 %, recovery of 70.53 %, while the ore of K₂ O in tailing is 9.53 %, recovery of 52.80 %.（3） The grain size analysis of raw ore and flotation ore show that under the identical flotation parameters, the smaller the mineral grain size, the higher the flotation recovery rate, while the grain size has negligible effect on the recovery rates of phosphate concentrate, potassium concentrate and raw ore. The comparison of the grades of coarse and fine phosphate and potassium concentrates shows that the grain size has negative effect on flotation.（4） The potassium concentrate（phosphate tailings） with K₂ O grade of 9.41 % reaches 10.94% after further flotation with the floation solution pH being 2 and dodecylamine being 3×10-4 mol/L, while the K₂ O grade reaches 10.53 % when pH is 8 and N- dodecyl-1,3-diaminopropanes is 4×10-4 mol/L.（5） The analysis shows that,after the trail of desilicication the concentration of K₂ O recovery rate is low while K₂ O in tailings grade is high may due to the following three reasons: firstly, the electrostatic effect resulting from amine collector cannot separate the feldspar and quartz by physical adsorption due to lacking selectivity because the feldspar and quartz basically have the same surface charge; secondly, mica will be preferentially flotated under the strong acid conditions due to a large amount of clay and iron impurities contained in the ores and the metasomatism of feldspar and sericite, resulting in low grade of K₂ O in the concentrate; thirdly, the fine-grained feldspar in the ores will adsorb on the surface of coarse-grained quartz, resulting in the flotation tailings containing fine grained feldspar and the low-efficient separation of feldspar and quartz.