柠檬酸在含碳酸盐赤铁矿浮选体系中的分散机理

以赤铁矿、菱铁矿和石英为研究对象,通过沉降试验、Zeta电位测试、傅里叶红外光谱分析和溶液化学计算研究了柠檬酸在强碱性条件下(pH=11.0)的分散机理.沉降试验结果表明,柠檬酸对人工混合矿(赤铁矿-菱铁矿-石英)具有较好的分散效果.动电位和红外光谱测试表明,柠檬酸在赤铁矿和菱铁矿表面的吸附较强烈并使其动电位负移,而在石英表面的吸附较弱并对石英动电位影响较小.溶液化学计算表明,柠檬酸主要以[C_6H_5O_7]~(3-)的形式吸附在赤铁矿和菱铁矿的羟基化表面,进而阻止矿粒间的凝聚.结果表明柠檬酸在含碳酸盐赤铁矿浮选体系中具有分散作用.     

聚氧化乙烯絮凝微细粒高岭石强化赤铁矿反浮选脱硅机理研究

通过矿物浮选试验并结合激光粒度测试、扫描电镜(SEM)、矿物Zeta电位及XPS等检测方法对赤铁矿反浮选过程中聚氧化乙烯絮凝细粒高岭石的行为及机理进行了研究.矿物絮凝浮选试验表明：添加聚氧化乙烯可以提高高岭石的单矿物回收率和人工混合矿分离效率,促进赤铁矿和高岭石反浮选分离.激光粒度测试和扫描电镜检测结果表明：聚氧化乙烯不絮凝赤铁矿,但絮凝高岭石颗粒,使其表观粒径增大.Zeta电位测试和XPS分析表明：聚氧化乙烯在高岭石颗粒表面发生化学吸附,并使其Zeta电位正移.因此,开展聚氧化乙烯对硅酸盐矿物絮凝的研究对赤铁矿和高岭石反浮选分离具有意义.     

细粒滑石对孔雀石硫化浮选的影响

通过浮选试验发现细粒滑石的加入降低了孔雀石的硫化浮选可浮性,细粒滑石含量越多,对孔雀石的可浮性影响越大;通过Zeta电位测试、吸附量测试、SEM-EDS分析和EDLVO理论计算研究分析了细粒滑石影响孔雀石硫化浮选的原因.结果表明:适量的Na₂S在孔雀石矿物表面的吸附是其硫化-黄药浮选成功的关键,而细粒滑石会吸附罩盖在孔雀石矿物表面,且滑石矿物表面不会发生Na₂S的吸附,因此,细粒滑石减弱了孔雀石矿物表面的硫化效果,使其可浮性降低.     

磁种磁团聚强化淀粉对微细粒赤铁矿的抑制

针对赤铁矿反浮选过程中，淀粉对微细粒赤铁矿抑制作用较差的问题，通过浮选试验、EDLVO理论计算、粒度分布和SEM分析，研究了利用磁种磁团聚强化淀粉对微细粒赤铁矿的抑制作用.结果表明，随着赤铁矿的粒度降低，淀粉对赤铁矿的抑制作用变差.添加磁铁矿可强化淀粉对微细粒赤铁矿的抑制作用，随着磁铁矿粒度的增加，强化抑制作用越明显.不同粒级的磁铁矿与微细粒赤铁矿间均存在引力作用，可使磁铁矿与赤铁矿发生磁团聚，且磁铁矿粒度越大，引力作用越强.磁团聚作用增加了微细粒赤铁矿的表观粒度，从而强化了淀粉对微细粒赤铁矿的抑制作用.     

粒度分布对赤铁矿浮选的影响

以赤铁矿为研究对象,通过浮选试验、扩展的DLVO(EDLVO)理论和凝聚动力学研究了粒度分布(粒径小于18μm的微细粒比例)对赤铁矿浮选的影响.浮选结果表明赤铁矿的浮选回收率与粒度的大小和分布有关,粗粒(粒径大于18μm)赤铁矿的粒度较大时或粒度分布均衡时(微细粒与粗粒含量接近)浮选回收率较高.EDLVO理论计算表明微细粒赤铁矿与粗粒赤铁矿之间存在吸引力,且吸引力的大小与粗粒粒度正相关;凝聚动力学分析表明粒度分布均衡时颗粒间的凝聚速率较大.这是粒度分布对赤铁矿的浮选回收率产生影响的主要原因.     

油酸钠与微细粒黑钨矿的作用机理

通过浮选实验、溶液化学计算、吸附量测试、动电位和红外光谱分析等方法,系统研究了油酸钠对微细粒黑钨矿的浮选捕收机理.结果表明:黑钨矿可浮性与油酸钠吸附量正相关,微细粒黑钨矿可浮性较好的pH区间为7.0～9.0,溶液中油酸离子和离子-分子缔合物组分对黑钨矿浮选过程起主要作用.溶液化学计算表明:油酸钠的吸附量和黑钨矿的可浮性与金属阳离子形成的油酸盐组分浓度有直接关系;油酸钠的添加使荷负电的黑钨矿动电位负移.红外光谱分析表明油酸钠在黑钨矿表面发生化学吸附,生成金属油酸盐,进而增强了黑钨矿的可浮性.     

烷基羟丙基胺作用下石英和赤铁矿的浮选行为

通过浮选试验研究了新型捕收剂烷基羟丙基胺(NDIA)作用下石英和赤铁矿的浮选行为,并结合量子化学计算和zeta电位分析,考察了该捕收剂在矿物表面的吸附机理.单矿物浮选试验结果表明:当捕收剂用量为33.33 mg/L,p H值为4.50~8.00时,石英的回收率在92%以上,赤铁矿的回收率在50%左右.人工混合矿分选试验结果表明:当捕收剂用量为33.33 mg/L,淀粉用量为13.33 mg/L,p H值为4.50~8.00时,NDIA均可实现石英和赤铁矿的有效分离.量子化学计算结果表明,与十二胺相比,NDIA对石英具有更好的捕收性能.zeta电位测试结果表明:NDIA在石英和赤铁矿表面均发生了吸附,且在石英表面的吸附作用强于赤铁矿.     

油酸钠直接浮选孔雀石的机理研究

研究了油酸钠直接浮选孔雀石的浮选行为及作用机理.采用浮选试验、Zeta电位测试、傅里叶红外光谱测试、溶液化学计算及热力学计算进行吸附机理分析.浮选试验表明:当捕收剂油酸钠用量为160 mg/L、pH值范围7~10时,孔雀石浮选回收率可以达到70%以上;当pH=9.5时,回收率为88.67%,达到最高;动电位及溶液化学表明:油酸钠在矿浆中的组分为C_(17)H_(33)COOH·C_(17)H_(33)COO~-,C_(17)H_(33)COO~-和(C_(17)H_(33)COO)_2~(2-),油酸钠在孔雀石表面主要发生了化学吸附;根据吉布斯自由能的计算和红外光谱测试分析表明:在合适的p H值范围,油酸钠与孔雀石表面的铜离子作用生成油酸铜盐沉淀,改变了孔雀石的表面性质使它表面疏水从而容易浮选回收.     

改性聚丙烯酰胺对赤铁矿强磁选的影响

基于聚团分选理论,采用改性聚丙烯酰胺(HPM)选择性聚团调浆-湿式强磁选工艺,考察了药剂用量、矿浆pH以及搅拌转速等因素对微细粒赤铁矿强磁分选效果的影响.通过扫描电镜检测、EDS能谱分析、动电位测试以及红外光谱检测等方法研究了物料聚团磁选前后的微观形貌以及药剂作用后矿物表面特性的变化,分析了药剂与矿物表面的作用机理.结果表明:在药剂用量10g/t、矿浆pH 10、搅拌转速954r/min的条件下,采用“选择性聚团-强磁选工艺”与常规强磁选工艺指标相比,精矿铁回收率提高了5.39%.添加HPM调浆后原矿中矿物颗粒表观粒径显著增加,在强磁选作业中添加HPM调浆能够强化对微细粒赤铁矿的回收,HPM对赤铁矿具有选择性絮凝聚团作用,且在赤铁矿表面存在静电吸附和氢键吸附,在石英表面不发生吸附作用.     

微细粒混合磁选精矿分级—分散浮选试验研究

针对东鞍山混合磁选精矿进行了预先分级—强化分散浮选试验研究，同时结合沉降试验、动电位测试、浊度测试等分析了分选效果改善的原因.在最优条件下分级—分散浮选闭路试验可获得精矿铁品位66.24%、铁回收率79.47%的浮选指标，与单一分散浮选的闭路试验相比，精矿铁回收率提高了4.47%.沉降试验和浊度测试表明，分散剂柠檬酸及粒度组成均会影响赤铁矿-石英混合矿的分散特性，柠檬酸主要吸附在赤铁矿表面从而增大矿粒间的静电斥力，优化粒度组成实现窄级别浮选则会进一步减弱矿粒间的非选择性团聚(罩盖)，为后续浮选分离创造有利条件，这也与DLVO理论及团聚动力学的分析结果基本一致.     

Improved flotation performance of hematite fines using citric acid as a dispersant

In this study, citric acid was used as a dispersant to improve the flotation performance of hematite fines. The effect and mechanism of citric acid on the reverse flotation of hematite fines were investigated by flotation tests, sedimentation experiments, scanning electron microscopy (SEM), zeta-potential measurements, and X-ray photoelectron spectroscopy (XPS). The results of SEM analysis and flotation tests reveal that a strong heterocoagulation in the form of slime coating or coagulation in hematite fine slurry affects the beneficiation of hematite ores by froth flotation. The addition of a small amount of citric acid (less than 300 g/t) favorably affects the reverse flotation of hematite fines by improving particle dispersion. The results of sedimentation experiments, zeta-potential measurements, and XPS measurements demonstrate that citric acid adsorbs onto hematite and quartz surfaces via hydrogen bonding, thereby reducing the zeta potentials of mineral surfaces, strengthening the electrical double-layer repulsion between mineral particles, and dispersing the pulp particles.     

Effect of sodium alginate on reverse flotation of hematite and its mechanism

Given the gradual increase in the chlorite content of hematite ores, pulp properties seriously deteriorate during flotation. The traditional anion reverse flotation of hematite cannot effectively eliminate the effects of chlorite, leading to a significant decrease in the total Fe (TFe) grade of the concentrate. In this work, the effect of sodium alginate on the reverse flotation of hematite was systematically investigated. Flotation tests of artificially mixed ores were conducted, and the results showed that sodium alginate can significantly improve the removal rates of quartz and chlorite. The adsorption measurements, infrared spectroscopy, and contact angle tests demonstrated that sodium alginate adsorbs on the quartz surface by chelating with calcium ions, thereby weakening the steric hindrance of oleate ions and increasing the adsorption capacity of sodium oleate to ultimately improve the removal rate of quartz. Furthermore, owing to its lower density and fine particle size, chlorite is easily entrained into the foam layer. Sodium alginate dramatically increases the liquid-to-gas ratio of the foam layer by increasing pulp viscosity, thereby increasing the entrainment rate of chlorite and finally improving its removal rate. The core content of this thesis bears significance in improving the Fe grade in the reverse flotation of chlorite-containing hematite.     

Effect and mechanism of siderite on reverse flotation of hematite

The effects of siderite on reverse flotation of hematite were investigated using micro flotation, adsorption tests, and Fourier transform infrared spectroscopy. The flotation results show that interactions between siderite and quartz are the main reasons that siderite significantly influences the floatability. The interactions are attributed to dissolved siderite species and fine siderite particles. The interaction due to the dissolved species is, however, dominant. Derjaguin-Landau-Verwey-Overbeek (DLVO) theoretical calculations reveal that adhesion on quartz increases when the siderite particle size decreases and that fine particles partly influence quartz floatability. Chemical solution calculations indicate that the dissolved species of siderite might convert the surface of active quartz to CaCO₃ precipitates that can be depressed by starch. The theoretical calculations are in good agreement with the results of adsorption tests and FTIR spectroscopy and explain the reasons why siderite significantly influences reverse flotation of hematite.     

Solution chemistry of carbonate minerals and its effects on the flotation of hematite with sodium oleate

The effects of carbonate minerals (dolomite and siderite) on the flotation of hematite using sodium oleate as a collector were investigated through flotation tests, supplemented by dissolution measurements, solution chemistry calculations, zeta-potential measurements, Fourier transform infrared (FTIR) spectroscopic studies, and X-ray photoelectron spectroscopy (XPS) analyses. The results of flotation tests show that the presence of siderite or dolomite reduced the recovery of hematite and that the inhibiting effects of dolomite were stronger. Dissolution measurements, solution chemistry calculations, and flotation tests confirmed that both the cations (Ca2+ and Mg2+) and CO₃2- ions dissolved from dolomite depressed hematite flotation, whereas only the CO₃2- ions dissolved from siderite were responsible for hematite depression. The zeta-potential, FTIR spectroscopic, and XPS analyses indicated that Ca2+, Mg2+, and CO₃2- (HCO₃-) could adsorb onto the hematite surface, thereby hindering the adsorption of sodium oleate, which was the main reason for the inhibiting effects of carbonate minerals on hematite flotation.     

细粒浮选体系中界面极性相互作用理论及应用

本文系统讨论了界面极性相互作用理论及其在细粒浮选研究中的应用。亲水矿粒间水化排斥作用及疏水矿粒间疏水吸引作用主要归因于颗粒间界面极性相互作用。通过测定矿物在已知表面能参数的液体中的接触角,就可确定矿物的表面能参数值。由界面极性相互作用能确定水化或疏水相互作用能量常数,从而计算颗粒间水化或疏水相互作用能曲线,利用EDLVO理论能很好解释矿粒间的凝聚、分散行为。     

Morphological and mineralogical characterizations of oolitic iron ore in the Exi region, China

The morphological and mineralogical characterizations of a Chinese oolitic iron ore (Exi deposit) were studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy in this work. It is shown that the Exi ore is mainly composed of hematite, quartz, apatite, and chlorite. The hematite is present as the oolitic layers and in the spaces between the aggregated ooids; quartz exists as granular particles in the spaces and as nucleuses in ooids; the harmful mineral, apatite, is associated with hematite as the oolitic layers, fine dissemination, granular particles in the spaces, and nucleuses in ooids. From the viewpoint of mineral beneficiation, it is hard to separate apatite and chlorite but easy to separate quartz from hematite in the Exi iron ore in recovering the iron values.