辉钼矿与滑石浮选药剂研究进展

Research Progress in the Flotation Reagent of Molybdenite and Talc

辉钼矿和滑石共伴生关系密切且可浮性相近,因此两者的高效分离一直是浮选领域的难点。目前辉钼矿-滑石分离工艺主要有浮钼抑滑石的正浮选和先浮选脱除滑石再浮钼的反浮选两类,两种工艺都涉及辉钼矿与滑石的抑制剂和辉钼矿捕收剂。近些年来报道了很多辉钼矿-滑石分离的新型药剂,但是缺乏对药剂化学组成、官能团和空间构型等方面相似性、递变性和差异性的系统总结和分析。因此,在总结了目前辉钼矿和滑石晶体结构与亲/疏水特性的研究进展基础上,较详细论述了辉钼矿和滑石抑制剂类型、吸附机理和应用效果,分析了抑制剂作用的构效关系,并介绍了辉钼矿/滑石抑制剂和辉钼矿捕收剂的分子设计最新进展。通过总结晶体结构和基面/端面的亲/疏水性性质,发现两种矿物的端面都存在离子溶解、氧化等行为,导致其亲水性较强,但由于基面占据了整体表面积的90%以上,因此两种矿物整体上表现出较好的天然疏水性,这是其浮选分离困难的根本原因。水溶性金属盐是传统的辉钼矿和滑石的无机抑制剂,存在用量大、选择性差的缺点,因而其应用受到限制。有机高分子物质是辉钼矿/滑石抑制剂的研究热点,该类药剂在矿浆中往往表现为酸性,此时辉钼矿/滑石表面的碱度越高,两者间的相互作用就越强;在“强相互作用”时,这种酸碱相互作用可能表现为化学吸附,而在“弱相互作用”时,该作用表现为疏水吸引、氢键吸引、静电吸引等形式的弱吸附,这类抑制剂包括目前大量报道的多糖、腐殖酸等。因此,基于抑制剂在官能团种类与数量、空间构型等因素作用下与两种矿物的基/端面的Mo/Mg金属位点吸附的构效关系,采用组合或者接枝合成等方式设计高选择性分子结构,是开发辉钼矿/滑石抑制剂的思路之一。传统辉钼矿捕收剂以烃油类和巯基类药剂为主,但分别存在分散性差和对辉钼矿-硫化矿脉石的选择性差的缺陷,因此在烃油类捕收剂基础上,从捕收剂分子与辉钼矿端面暴露位点、氧化组分、溶解组分的化学作用出发,设计含有N、P、S等元素的高选择性捕收剂,实现表面氧化、溶解严重的微细粒辉钼矿的选择性捕收,是辉钼矿捕收剂分子设计的方向之一。抑制剂和辉钼矿捕收剂是辉钼矿和滑石浮选分离的关键,设计绿色高效的新型药剂对辉钼矿的开发具有重要意义。

Molybdenite and talc are closely associated with each other and have similar floatability,so their efficient flota-tion separation is always a difficulty in flotation field.At present,the separation process of molybdenite and talc mainly includes positive flotation by floating molybdenite and reverse flotation by removing talc and then floating molybdenum.Both processes involve the inhibitor of molybdenite and talc and collector of molybdenite.In recent years,many new reagents for molybdene-talc separation have been reported,but there is a lack of systematic summary and analysis of the similarity,variability and difference of these reagents in terms of chemical composition,functional groups and steric configuration.Therefore,the research progress on the relationship between crystal structure and hydrophilic/hydrophobic properties of molybdenite and talc is sum-marized.The types,adsorption mechanism and application effect of molybdenite and talc inhibitors are discussed in detail.The structure-activity relationship of inhibitors is analyzed,and the latest progress in molecular design of molybdenite/talc inhibitors and molybdenite collectors is introduced.By summarizing the crystal structure and hydrophilic/hydrophobic characteristics of the basal/edge plane,it is found that the two minerals have strong hydrophilic properties due to ionic dissolution,oxidation and other behaviors on the edge planes.However,as the basal plane occupies more than 90%of the overall surface area,the two minerals show good natural hydrophobicity as a whole,which is the fundamental reason for the difficulty in flotation separation.Water-soluble metal salt is the traditional inorganic inhibitor of molybdenite and talc,but it has the disadvantages of large dos-age and poor selectivity,so its application is limited.Organic polymers are the research focus of molybdenite/talc inhibitors,which are often acidic in the pulp.The higher the alkalinity of the surface of molybdenite/talc,the stronger the interaction be-tween them.When the adsorption is"strong interactions",this acid-base interaction may appear as chemisorption;when the ad-sorption is"weak interaction",the effect is manifested as hydrophobic attraction,hydrogen bond attraction,electrostatic attrac-tion and other forms of weak adsorption.Such inhibitors include polysaccharide,humic acid and so on.Therefore,based on the structure-activity relationship between the inhibitors and Mo/Mg sites on the basal/edge planes of the two minerals under the actions of functional group type and number,steric configuration and other factors,the design of highly selective molecular structures by combination or grafting synthesis is one of the ideas for the development of molybdenite/talc inhibitors.The tradi-tional collectors of molybdenite are mainly hydrocarbon oils and sulfhydryl compounds,but there are defects of poor dispersity and poor selectivity to molybdenite and sulfide gangue minerals respectively.Therefore,on the basis of hydrocarbon oil collec-tor,from the perspective of the chemical interaction between collector molecules and the exposed sites on the edge planes,oxi-dation components and dissolved components,designing highly selective collectors containing N,P,S and other elements to a-chieve selective collecting of the fine-grained molybdenite with severe surface oxidation and dissolution is one of the develop-ment directions of molybdenite collector molecules.Inhibitors and molybdenite collectors are the keys to the separation of mo-lybdenite and talc.It is of great significance to design green and efficient new reagents for the development of molybdenite.