Research On The Mechanism And Industrialization Of Zinc Flotation In Sulfur Concentrate With Combined Depressant M

The sulfur concentrate produced by the concentrator of Yiliang Chihong Mining Co.,Ltd,contains a small amount of lead-zinc minerals,which leads to high impurity content and will be sold at a discount.Therefore,it is of great practical and economic significance to carry out new beneficiation technology research on the high-sulfur sulfur concentrate,recovering the lead-zinc minerals,producing lead-zinc mixed product and high-quality sulfur concentrate,and improving the comprehensive utilization level of lead-zinc-sulfur resources.As a conventional pyrite depressant,lime has the following disadvantages of large dosage,easy blockage of pipelines and high cost of backwater treatment,in the process of flotation of lead-zinc minerals from sulfur concentrate.Therefore it is of great practical significance to develop a green and efficient new pyrite depressant under low alkalinity conditions for improving lead-zinc ore recovery and upgrading the sulfur concentrate.Firstly,the flotation tests of sphalerite and pyrite pure minerals and artificial mixed minerals were carried out to study the flotation behavior of sphalerite and pyrite in the presence of combined depressants.A combined depressant MS（sodium dithionite and lignosulfonate were prepared in a ratio of 40:1）was developed.The test results in the flotation separation experiments of artificial mixed ore with different proportions showed that sphalerite and pyrite can be effectively separated when the alkalinity pH value was 10,the concentration of combined depressant MS was 6×10^-4mol/L,the concentration of copper sulfate was 6×10^-4mol/L,and the concentration of butyl sodium xanthate was 6×10^-4mol/L,the recovery rate of sphalerite was more than 88.92%,and the recovery rate of pyrite was less than 7.96%.The mechanism of surface hydrophobicity change of sphalerite and pyrite caused by combined depressant MS was elucidated by atomic force microscopy（AFM）imaging technology,X-ray photoelectron spectroscopy（XPS）fitting,Fourier transform infrared spectroscopy（FT-IR）analysis.Under the condition of low alkalinity（pH=10）,when the combined depressant MS existed,it was observed by AFM that the highest peak of the cross section height of pyrite exceeded 16 nm,the surface of pyrite was rougher,and the surface of pyrite had a high degree of reaction with the depressant.Through XPS,it was found that in the presence of combined depressant MS,after adding CuSO₄,the polysulfides on the surface of sphalerite increased significantly,which increased its reactivity and reaction sites.At the same time,the concentration of Cuatoms on the surface of pyrite decreased from 0.18% without adding the combined inhibitor MS to 0.06%when adding it.and the surface of pyrite was covered with a large number of hydrophilic Fe（Ⅲ）-O-OH components,and the hydrophobicity was reduced.It was found by FT-IR that there was no absorption peak of NaBX in the infrared spectrum of pyrite+combined depressant MS+CuSO₄+NaBX,and the amount of NaBX adsorbed on the surface of pyrite was very small.There was an absorption peak in the spectrum of sphalerite,and the amount of NaBX adsorbed on the surface changed little.In summary,when the combined depressant MS is present,it has a significant inhibitory effect on the pyrite activated by CuSO₄,but has no significant inhibitory effect on sphalerite,thus achieving the separation of the two under low alkalinity（pH=10）conditions.The interaction configuration ofS₂O₄^2-on the surface of ZnS（1 1 0）and FeS₂（1 0 0）was simulated by density functional theory（DFT）,and the mechanism ofS₂O₄^2--on FeS₂was further studied.It was founded that after the interaction betweenS₂O₄^2-ion and mineral surface,two SO₂^-ions were formed on the surface of ZnS（1 1 0）,and no chemical adsorption occuring,which had little effect on its hydrophobicity.On the surface of FeS₂（1 0 0）,Fe interacted strongly with O 2p and S 3p through Fe 3p 3d 4s orbitals.The strong chemical interaction between S,O and Fe hindered the adsorption of collector on the pyrite surface.The actual mineral process mineralogy research shows that the content of pyrite in the sulfur concentrate is as high as 95.40%,and the content of galena and sphalerite is relatively small,which is 1.10%and 2.64%respectively.Sphalerite belongs to fine disseminated mineral,the main particle size range is-75+2.9μm;the lead-zinc ore belongs to the fine disseminated particle size particles,the main particle size range is-45+2.9μm,and the lead-zinc ore and pyrite mineral dense symbiotic relationship is complex,the liberation degree is low,which bring difficulties to separate lead-zinc minerals from pyrite effectively.According to the ore characteristics of high-sulfur low-lead-zinc-sulfur concentrate,a small-scale experimental study and an expanded continuous flotation test were carried out by using the process of sulfur suppression priority flotation lead-zinc and rough concentrate regrinding and reconcentration.The pH of the pulp was adjusted to 10 by adding sodium hydroxide,copper sulfate was used as activator,combined depressant agent MS was used as depressant,collector butyl xanthate and foaming agent 24 K were added.Good beneficiation technical indicators were obtained.In the expanded continuous flotation test,a lead-zinc mixed concentrate containing 42.93%zinc,15.31%lead,60.95%zinc recovery and 34.03%lead recovery was obtained.The contents of lead and zinc in sulphur concentrate decreased significantly,only 0.74%and 0.69%respectively,and the quality of sulphur concentrate was improved significantly.At the end of September 2017,an industrial application production line suitable for high-sulfur low-lead-zinc sulfide concentrate was built and put into operation,which was composed of traditional flotation machine,jet flotation machine and vertical mill.when the dosage of sodium hydroxide and MS were respectively 1407g/t and 840g/t,pyrite can be well depressed,obtaining lead-zinc mixed concentrate.During the four-year technical service contract period ending July 2021,a total of 23300 tons of mixed concentrate with zinc grade of29.92%and lead grade of 13.09%.The recovery rates of lead and zinc metals in Yiliang Chihong Mining Co.,Ltd.were increased by 2.44%and 2.02%,respectively.At low alkalinity（pH=10）,pyrite can be well depressed by using combined depressant MS as depressant,producing marketable lead-zinc mixed products,the content of lead and zinc in sulfur concentrate was greatly reduced,and the quality of sulfur concentrate was improved.The comprehensive recovery of lead,zinc and sulfur resources in high-sulfur and low lead-zinc refractory sulfur concentrate was realized,which has obvious economic and social benefits.At the same time,the related technological innovation and cooperation mode construction have good reference significance for the improvement of sulfur concentrate quality and impurity reduction and the improvement of metal comprehensive recovery rate in similar mines in China.Laboratory tests and industrial application practice show that the combined depressant MS can be used to effectively depress pyrite at low alkalinity（pH=10）.It has the advantages of convenient configuration and addition,no blockage of pipelines,and low cost of backwater treatment.It is in line with the current development trend of green environmental protection in mineral processing production and has a wide application prospect.