【作者】 王超；

【导师】 孙春宝；

【作者基本信息】 北京科技大学 ， 矿物加工工程， 2022， 博士

【摘要】 微细粒矿物在浮选过程中容易造成有价矿物回收率低和亲水脉石矿物机械夹带的问题,这是利用浮选法有效分离微细粒矿物的挑战性所在。目前大多数研究着重提高微细粒目的矿物的回收率,但是仍然高度分散在浮选矿浆中的微细粒亲水矿物(通常是脉石),由于其粒度和质量非常小,无法克服流体拖曳力而易以机械夹带的形式被运移至浮选精矿中,从而造成精矿品位和浮选分离效率的降低。根据“物以类聚”的思想,论文提出通过类聚絮凝提高微细粒矿物浮选分离效率的新方法。通过分别絮凝疏水矿物和亲水矿物,形成表观粒径适宜的疏水絮团和亲水絮团,然后再进行浮选分离。该方法在浮选过程中可同时减少微细粒脉石矿物的机械夹带和强化微细粒目的矿物的浮选回收。论文以类聚絮凝-浮选为核心研究思路,以减少微细粒脉石矿物机械夹带、强化微细粒目的矿物浮选回收、类聚絮凝-浮选提高微细粒矿物的浮选分离效率为研究主线,针对D50、D90分别为2.4 μm、6.2μm的微细粒方铅矿和D50、D90分别为3.7 μm、11.1 μm的微细粒石英及二者的人工混合矿样为研究对象,对聚合氯化铝(PAC)和聚氧化乙烯(PEO)作用下的类聚絮凝、浮选分离及其作用机理展开了深入研究。微细粒石英浮选夹带行为的类聚调控研究表明,PAC能够有效减少微细粒石英的机械夹带,提高浮选分离效率。PAC可将石英夹带回收率从9.2%减少至5%、浮选分离效率从73.9%提高到80%。研究表明,PAC减少石英机械夹带的机理是PAC絮凝微细粒石英形成了石英絮团,但对微细粒方铅矿没有表现出絮凝作用。PAC在石英表面的吸附速率大于方铅矿,在方铅矿-石英矿浆体系中PAC会优先吸附于石英表面,因此较低浓度的PAC不会降低方铅矿的浮选回收率,但其浓度大于150mg/L后,PAC和乙基黄药(KEX)的加药顺序对方铅矿的浮选回收率有很大影响,“KEX+PAC”加药顺序(先加KEX)的浮选指标优于“PAC+KEX”(先加PAC)加药顺序的浮选指标。微细粒方铅矿浮选过程的类聚强化研究表明,将分子量为100万的PEO和KEX联合使用能够有效强化混合矿样中微细粒方铅矿的浮选回收,提高浮选分离效率。研究发现分子量为800万的PEO能够絮凝微细粒方铅矿和石英,没有选择性,分子量为100万的PEO则不能直接絮凝微细粒方铅矿或石英,但是经过KEX作用后,分子量为100万的PEO能够显著絮凝方铅矿,而对微细粒石英仍没有表现出絮凝作用,与“PEO+KEX”加药顺序相比,“KEX+PEO”加药顺序更有利于絮凝方铅矿,也更有利于强化方铅矿浮选回收。尽管泡沫稳定性研究表明PEO因增强泡沫稳定性而会略微增大微细粒石英的机械夹带,但是联合使用KEX和PEO可将方铅矿回收率从83.1%提高至94%、浮选分离效率从73.9%提高至82%。基于微细粒石英浮选夹带行为的类聚调控和微细粒方铅矿浮选过程的类聚强化的研究基础,深入展开了微细粒方铅矿和石英体系类聚絮凝-浮选的研究,其中PAC、PEO和KEX这三种药剂在矿物表面的吸附顺序及吸附量起决定性作用。联合使用这三种药剂且加药顺序为“KEX+PEO+PAC”,石英夹带回收率从9.2%减少至6.6%、方铅矿回收率从83.1%提高至90.2%,浮选分离效率从73.9%提高至83.6%,既减少了微细粒石英的机械夹带,又强化了微细粒方铅矿的浮选回收。这是由于黄原酸盐在方铅矿颗粒表面发生化学吸附,增大了方铅矿的疏水性,PEO的单个分子链可通过其中的-CH2-CH2-以疏水作用力的机制吸附到多个方铅矿颗粒上,而PAC水解产物中的亲水铝羟基吸附于方铅矿上降低其疏水性,弱化了“KEX+PEO”加药顺序对微细粒方铅矿的絮凝效果;先加入的KEX减少了 PAC在方铅矿颗粒表面的吸附量,黄原酸盐在方铅矿颗粒表面的化学吸附能够在一定程度上抑制PAC在方铅矿表面的吸附;QCM-D分析表明,先添加的PEO几乎不影响PAC在石英表面的吸附。因此,“KEX+PEO+PAC”加药顺序最有利于分别絮凝微细粒方铅矿和微细粒石英,通过类聚絮凝实现提高微细粒矿物浮选分离效率的目的。为絮凝表面荷负电的微细粒亲水脉石矿物,可选择水解组分主要为阳离子的高分子聚合物或阳离子絮凝剂,综合考虑PAC的絮凝能力和因亲水性对疏水矿物疏水性的影响,PAC不会对疏水矿物表现出絮凝作用;捕收剂作用于矿物表面对PEO的吸附和絮凝作用具有协同效应,PEO是一种絮凝微细粒疏水矿物的有效絮凝剂,通过利用捕收剂作用于目的矿物表面增大表面疏水性和选择适宜分子量的PEO,将PEO和捕收剂联合使用能够选择性絮凝微细粒疏水矿物。论文研究成果不只限于PAC、PEO、方铅矿和石英组成的药剂-矿物浮选体系,捕收剂作用于矿物表面对聚合物吸附的协同效应及由此产生的选择性可能同样存在于其他的药剂-矿物浮选体系中,通过调整药剂制度进行界面调控,形成有利于分别絮凝微细粒疏水矿物和亲水矿物的先决条件,实现通过类聚絮凝提高微细粒矿物浮选分离效率的目的。更多还原

【Abstract】 Microfine mineral particles in froth flotation pose two serious problems,i.e.,the low recovery of the value minerals and the mechanical/hydraulic entrainment of the hydrophilic gangue minerals.As a result,effective separation of the microfine minerals by flotation is a major challenge.Most of the current studies focus on improving the flotation of the microfine hydrophobic particles,but the microfine hydrophilic particles(usually gangue minerals),which are still highly dispersed in the flotation pulp,cannot overcome the fluid drag force and are easily transported into the flotation concentrate by mechanical entrainment due to their small size and mass,resulting in a reduction in concentrate grade and flotation separation efficiency.According to the material property of "birds of a feather flock together",a research idea clustering flocculation of the microfine minerals is proposed in this thesis to improve flotation separation efficiency.In the proposed process,the hydrophobic and hydrophilic minerals are separately flocculated to form the hydrophobic and hydrophilic flocs,respectively,with appropriate floc apparent particle sizes,followed by flotation separation.This method can simultaneously lower the entrainment of the gangue minerals and enhance the flotation recovery of the microfine value minerals.The core research idea of clustering flocculationflotation was studied,lowering the microfine gangue minerals,enhancing the flotation recovery of the microfine value minerals,and improving flotation separation efficiency by clustering flocculation-flotation were taken as the main research line,the microfine galena(D50 of 2.4 μm and D90 of 6.2 μm)and microfine quartz(D50 of 3.7 μm and D90 of 11.1 μm),and their synthetic mixtures were used as the samples.In this work,the directional double flocculation,flotation separation,and the mechanisms underpinning the research results induced by polyaluminum chloride(PAC)and polyethylene oxide(PEO)were deeply studied.The study of lowering entrainment of the microfine quartz particles showed that PAC could effectively reduce the entrainment of the microfine quartz to improve the flotation separation efficiency.The addition of PAC was able to lower the quartz entrainment from 9.2%to 5.4%,and the corresponding separation efficiency was improved from 73.9%to 80%.The study showed that the reduction of quartz entrainment was due to the formation of the homo-flocs of microfine quartz induced by PAC,but the addition of PAC did not show flocculation effect on microfine galena.The adsorption rate of PAC on quartz surfaces was found to be higher than on galena,and it was inferred that PAC preferentially adsorbed on quartz in the artificial galena-quartz mixtures.Therefore,lower concentrations of PAC did not reduce the flotation recovery of galena,but at higher PAC concentrations(>150 mg/L),the addition sequence of PAC and KEX was significant for the galena recovery,and the addition sequence of "KEX+PAC"(adding KEX first)generated better results than that of "PAC+KEX"(adding PAC first).The study of enhancing flotation of the microfine galena showed that the combination of a 1 million molecular weight(MW)PEO and the collector KEX could effectively enhance the galena recovery and improve the separation efficiency.Importantly,it was found that the PEO with a MW of 8 million unselectively flocculated both galena and quartz,but the 1 million MW PEO could not flocculate either galena or quartz.However,after the galena was treated with KEX,the 1 million MW PEO was able to flocculate the galena but it still did not show flocculation effect on microfine quartz.Compared with the addition sequence of"PEO+KEX",the addition sequence of "KEX+PEO" was conducive to flocculating the microfine galena,which led to the significantly enhanced flotation recovery of the microfine galena.Although the formability measurements indicate that PEO could enhance the foam stability,resulting in a slight increase in quartz entrainment,the combination of KEX and PEO significantly increased the galena recovery from 83%to 94%,and the separation efficiency was improved from 73.9%to 82%.Based on the study of lowering entrainment of microfine quartz particles and enhancing flotation recovery of microfine galena particles,the research on clustering flocculation-flotation of microfine galena and quartz was carried out indepth,in which the adsorption sequence and adsorption amount of PAC,PEO,and KEX played a decisive role.With the combined use of the three reagents and their adding sequence of "KEX+PEO+PAC",the quartz entrainment recovery was reduced from 9.2%to 6.6%,the galena recovery was increased from 83.1%to 90.2%,and thus the flotation separation efficiency was improved from 73.9%to 83.6%,which not only regulated the mechanical entrainment of the microfine quartz but also enhanced the flotation recovery of the microfine galena.This was due to the chemisorption of xanthate on the surface of galena particles increased its hydrophobicity,and thus the single molecular chain of PEO could be adsorbed to several galena particles through-CH2CH2-driving by the mechanism of hydrophobic force,while the hydrophilic aluminum hydroxyl groups in PAC hydrolysis products adsorbing on the galena reduced the hydrophobicity of galena,which weakened the flocculation effect of "KEX+PEO" on the microfine galena.The first addition of KEX reduced the adsorption of PAC on the galena surface,it was likely that the xanthate chemisorption could inhibit the adsorption of PAC on the surface of galena to some extent.QCM-D analysis showed that the first addition of PEO had little effect on the adsorption of PAC on the quartz surface.Therefore,compared with other dosing sequences,"KEX+PEO+PAC" was the most favorable to flocculate the microfine galena and quartz successively,achieving the research objective of improving the flotation efficiency of microfine minerals through clustering flocculation.PAC and other high molecular weight polymers whose hydrolysis products are mainly cationic components,or cationic flocculants could be chosen to flocculate the microfine hydrophilic gangue minerals with negative charges,PAC is a certain hydrophilic and its aggregation ability is not too strong.Combining its flocculation ability and the effect on the hydrophobicity of hydrophobic minerals,PAC may not exhibit flocculation on hydrophobic minerals.The collector acting on the mineral surface has a synergistic effect on adsorption and flocculation of PEO which is an effective flocculant for flocculating microfine hydrophobic minerals.The combined use of PEO and collector for the hydrophobic minerals could selectively flocculate the microfine hydrophobic particles,in which the adsorption of the collector increases the mineral surface hydrophobicity and the PEO with an appropriate molecular weight should be selected.The findings of this research are not just limited to the flotation system of PAC,PEO,galena,and quartz.The synergistic effect of the collector acting on the mineral surface on polymer adsorption and the resulting selectively should also exist in many other reagent-mineral systems,where interfacial regulation by adjusting the reagent regime creates the prerequisites for separate flocculation of the microfine hydrophobic and hydrophilic minerals to improve the flotation separation efficiency of microfine minerals through clustering flocculation.更多还原