Experimental Study On Flotation Separation Of Pyrite And Chalcopyrite At Low Alkalinity

With the gradual promotion of green mine construction and the increasing difficulty of copper-sulfur mineral resources,the traditional lime high-alkali copper-sulfur separation process also exposes some shortcomings.Nowadays,mineral processing workers are committed to developing various efficient collectors and inhibitors suitable for low-alkali copper-sulfur flotation separation.In this paper,the copper-sulfur ore in Dali,Yunnan Province was taken as the research object to explore a new reagent system suitable for the efficient separation of copper and sulfur under low alkalinity conditions.The traditional lime high alkalinity process is used in the field,and a total of 12000 g/t lime is used to adjust the pH value of each flotation stage to 12.The process is simple,but there are also shortcomings such as low recovery rate of copper concentrate,large fluctuation of pulp pH value and unstable foam layer.In addition,due to the large fluctuation of raw ore properties,it is difficult to obtain high-quality concentrate under the conditions of existing pharmaceutical system and high alkaline pulp.On the basis of referring to a large number of domestic and foreign data and referring to the field separation process,the actual mineral test in this paper mainly adopts the new inhibitor YT and lime to reduce the amount of lime and pulp pH value.In addition,copper collector MCO and foaming agent HCCL were used to improve the selection index.The pure mineral test was further used to verify the effect of YT and MCO in the actual mineral test.The main conclusions of this paper are as follows:（1）According to the analysis of process mineralogy,the ore is composed of multiple components,and has the characteristics of complex structure,fine dissemination of useful minerals,and close combination of copper and sulfur.The useful elements in the raw ore are copper,sulfur,iron,gold and silver.The grade of copper is 0.50%,the grade of sulfur is 6.62%,the grade of iron is 25.51%,the grade of gold is 0.76 g/t,and the grade of silver is 23.28 g/t.There are often chalcopyrite filling and metasomatism in the crystal gap or fracture of pyrite,and chalcopyrite is often encapsulated and scattered in pyrite.Combined with the screening results of raw ore particle size,it is difficult to achieve full monomer dissociation.（2）In the copper flotation section,the closed-circuit process simplified the first stage cleaning and first stage scavenging compared with the original plant,and the amount of lime was reduced by 10000 g/t,which successfully inhibited pyrite under low alkalinity conditions.Through a series of conditional tests,the closed-circuit process was finally determined as follows:floating copper was cleaned by one roughing,two cleanings and one scavenging.The copper grade in copper concentrate was 17.02%,and the recovery rate was 80.24%.Compared with the closed-circuit test data of the original plant process,it can be seen that the copper grade was only reduced by 0.31%,the copper recovery rate was increased by 3.26%,and the sulfur recovery rate was reduced by 2.13%.The separation effect of copper and sulfur was good.（3）By comparing the simulation data of the whole process of the original plant and the whole process of the new process,it is fully demonstrated that the new reagent system has no negative impact on the flotation of sulfur and iron.The sulfur concentrate with a grade of 45.21%and a recovery of 63.31%was obtained by the whole process of the new process through one roughing and two cleaning flotation.Compared with the whole process data of the original plant,the grade of the sulfur concentrate increased by 4.67 percentage points and the recovery increased by 12.04percentage points.The iron concentrate with a grade of 60.36%and a recovery of43.29%was obtained by two-stage magnetic separation in the whole process of the new process,which is close to the whole process data of the simulated original plant.（4）YT has selective inhibition to pyrite.The results of single mineral flotation test showed that YT had obvious inhibitory effect on pyrite.The tests of mixed ores with different proportions showed that YT had selective inhibitory effect,which was characterized by contact angle test and adsorption capacity test.The difference of YT adsorption rate between the two pure mineral surfaces reached 71.77%when the concentration was 30 mg/L,which fully illustrated that YT had selective adsorption.Zeta potential test shows that the interaction between YT and pyrite can significantly improve the value of isoelectric point,and the potential gap between YT and chalcopyrite is large in the low alkalinity range,which is beneficial to the separation of copper and sulfur.（5）MCO has selective collection of chalcopyrite.The results of single mineral flotation test showed that MCO was more selective than Z200,and the difference in pyrite recovery between MCO and Z200 reached 31.49%at the concentration of 24mg/L.The contact angle test results showed that when the MCO concentration increased to 56 mg/L,the maximum difference in surface wettability between the two minerals reached 3.53 J×10^-2/m².According to the infrared spectrum analysis of MCO and two minerals before and after interaction,the adsorption form of collector MCO and chalcopyrite is chemical adsorption.