Experimental Study On Quality Improvement Of Dahongshan Hematite-type Secondary Concentrate By Flotation

The iron grade of the secondary concentrate is higher than the iron grade of the rude ore and lower than that of the qualified concentrate,and it is produced in many iron ore concentrators.The secondary concentrate is low in price and difficult to sell,the large amount of secondary concentrate also causes waste of iron resources and environmental problems.Due to the implementation of reducing tailings in recent years,Yuxi Dahongshan Mining Co.,Ltd.,a subsidiary of the Kunming Iron&Steel Company,produced many secondary concentrates with a variety of grades and have been difficult to sell,which has affected the economic efficiency of enterprises.These minerals in secondary concentrate are complex in composition,with a wide variety of gangues,especially iron-containing silicates,making beneficiation difficult.Hematite-limonite is the main enrichment target for the upgrading and decontamination of secondary concentrates,but the Dahongshan iron ore deposit is a large-scale deposit that occurs in the marine volcanic eruption sedimentary metamorphic rocks of the Dahongshan Group in the Paleoproterozoic.Its type and characteristics of the hematite-limonite are different from other mines and have their own characteristics.It is difficult to achieve efficient treatment with a conventional single process.The issue of upgrading and decontamination of the Dahongshan-style hematite-limonite secondary concentrate has received a lot of attention,and companies and research institutes have also conducted a lot of researches.On the basis of previous researches,this work started from the most essential mineral crystals,and through test characterization and theoretical calculations,discovered the typical characteristics of the Dahongshan hematite-limonite crystals,and found the mineralogical and crystallographic reasons why it’s difficult to recover and separate with a single magnetic separation,and multi-group collectors have been developed,and more rational reagent regime has been explored.Then laboratory and industrial experiments were conducted.Research indicates:（1）Dahongshan Secondary Concentrate,mainly composed of hematite-limonite,formed a differentiated iron-containing mineral crystal structure in the process of mineralization and alteration,and hematite-limonite with the same chemical formula have different crystal geometry and electromagnetic structure,caused the difference in magnetic separation of different mineralization crystals in different alteration periods.Therefore,it is difficult for this part of the hematite-limonite to recover efficiently with a single magnetic strength and magnetic equipment.（2）The unique dissociation surface properties formed because of the different crystal structure caused by the relaxation and reconstitution,which provide a possibility for the flotation treatment of Dahongshan-style hematite-limonite.According to crystal bulk differentiation and surface characteristics,positive flotation multi-group collectors were synthesized.The laboratory positive flotation experimental study of 37%secondary concentrate,second-stage magnetic concentrate,second-stage centrifuge concentrate,and third-stage magnetic concentrate were respectively completed,and the industrial trials of 37%secondary concentrate and 50%secondary concentrate were completed respectively.Industrial trials have verified the stability and adaptability of flotation indicators under continuous conditions and new reagent regime,which provided a basis for technological upgrading.（3）The 37%secondary concentrate,the TFe grade of rude ore is 38.46%,the content of Si O₂ is 24.69%,was treated by the flotation process of“one roughing,two cleaning and middlings reconcentration”,the concentrate with 53.73%Fe grade and13.53%SiO₂ content was obtained,the Fe grade increased by 15.27 points and the SiO₂ content decreased by 11.16 points.For the second-stage magnetic concentrate after the process of“one roughing,one cleaning and one middlings reconcentration”,the grade of Fe was increased from 45.26%to 57.48%,the grade of SiO₂ was reduced from 20.07%to 7.56%,and the recovery of Fe was 81.59%.For the second-stage centrifuge concentrate,after the process of“one roughing,one cleaning and middlings reconcentration”,the grade of Fe was increased from 54.00%to 59.25%,the grade of SiO₂ was reduced from 10.90%to 5.57%,and the recovery of Fe was 83.74%.For the second-stage magnetic concentrates in the third concentrator,the process of“one roughing,one cleaning and middlings reconcentration”was used to obtain a concentrate with comprehensive Fe grade of 57.26%,a recovery of 75.14%,and a SiO₂ content of 5.26%,the grade of Fe increased by 13.02 points and the content of SiO₂ decreased by 14.04 points.（4）Industrial tests were conducted on 37%secondary concentrate.The grade of Fe in rude ore is 40.58%,the content of SiO₂ is 21.84%,the grade of Fe in final concentrate is 52.28%,the content of Si O₂ is 12.12%,the recovery of Fe is 74.46%,and the grade of Fe in iron concentrate increased by 11.7 points and the SiO₂decreased by 9.72 points.Industrial tests were conducted on 50%secondary concentrates.The grade of Fe in rude ore is 50.24%,the content of Si O₂ is 14.22%,the grade of Fe in final concentrate Fe is 57.79%,the content of SiO₂ is 8.09%,and the metal recovery is 82.08%.The important findings of the coexistence of polymorphs and different electromagnetic properties of the Dahongshan-stylehematite-limonite have been obtained.The multi-group collector agents based on the characteristic crystal surfaces has obtained and applied in laboratory and industrial experiments.The research has a positive progress.It laid the foundation for the final technological breakthrough of the Dahongshan hematite-type secondary concentrate,and also provided a reference for the recovery of hematite in other regions of the same type.