Fe(III) as an activator for the flotation of spodumene,albite, and quartz minerals

The effect of Fe(III) ions on the flotation of spodumene, albite, and quartz minerals using sodium oleate (NaOL) was investigated by micro-flotation tests, zeta-potential measurement space, pyrene fluorescence spectroscopy and X-ray photoelectron spectroscopy (XPS). These minerals were difficult to float in the presence of NaOL alone. However, when Fe(III) ions were used as the activator, the flotation of the minerals improved. Zeta potential testing found the addition of Fe(III) at pH conditions <8 to reduce the negative charge on the spodumene, albite and quartz surfaces, which supports a mechanism where Fe(III) adsorbs onto these mineral surfaces, resulting in an expected increase in NaOL collector adsorption with a concomitant increase in the flotation recoveries. Subsequent pyrene fluorescence spectroscopy of these minerals in the presence of NaOL collector, with and without Fe(III) activator, showed the mineral surfaces to switch from polar to non-polar.     

Selective flotation separation of spodumene from feldspar using new mixed anionic/cationic collectors

The selectivity in flotation separation of spodumene from other pegmatic aluminosilicates such as feldspar and mica, using a single fatty acid anionic collector, is found to be very difficult. It is attributed to the same surface Al site for interaction with fatty acid. In this study, a collector mixture of sodium oleate (NaOL) and dodecyl trimethyl ammonium chloride (DTAC) demonstrates a high selectivity for the flotation of spodumene from feldspar. The influences of important factors such as molar ratio of the mixed collectors, dosages of calcium chloride, sodium hydroxide and sodium carbonate, and pulp temperature on spodumene and feldspar flotation using the mixed collectors have been investigated through micro-flotation tests. The optimum molar ratio of NaOL and DTAC is found to be 9:1. Sodium hydroxide has to be used as a pH regulator. Without the use of depressants, no selectivity is observed as the flotation of spodumene and feldspar are activated by Ca²⁺. Sodium carbonate must be used as depressant of feldspar. A comparison of the flotation for a lithium pegmatite ore using mixed fatty acid soaps and mixed anionic/cationic collectors (NaOL/DTAC) was carried out by the batch flotation tests. The results indicated that NaOL/DTAC decrease collector consumption by two-thirds. The recovery and grade of Li₂O concentrates increase by 4.93% and 0.31%, respectively.     

流动注射原子吸收法测定光卤石中钙和镁

在ＨＣｌ介质中利用高含量的钠离子和硫酸根离子对镁的干扰效应及流动注入注入试样对镁的稀释效应，可对低含量的钙和高含量的镁用原子吸收法直接测定。方法简便，其分析速度为８０个样／ｈ。用于光卤石钙、镁测定，结果与络合滴定法结果一致。     

Synergetic effect of a mixture of anionic and nonionic reagents: Ca mineral contrast separation by flotation at neutral pH

Ca mineral flotation was performed to characterise the separation conditions of calcite, francolite, fluorite and gypsum at neutral pH. These minerals constitute the gangue of metallic or sedimentary ores. The separation of Ca minerals is difficult because of their similar surface properties. Thus, the effect of using different electrolytes on francolite zeta potential measurements was studied. Batch experiments were performed to generate scientific knowledge of Ca mineral flotation behaviour at neutral pH. This paper discusses the effect of mixing anionic collectors (sodium oleate, hydroxamic acid, D2EHPA) with nonionic reagents on the selective separation of Ca minerals. The most interesting observation is the separation of gypsum from other Ca minerals using a mixture of sodium oleate and nonionic reagents. Additionally, this paper discusses the enhancement of separation contrast between calcite and francolite by adding nonionic and anionic reagents.     

On the mechanism of the flotation of oxides and silicates

The mechanism of flotation of oxide and silicate minerals was established long ago as being due to the electrostatic attraction between the charged surface and the charge of the collector. What is less well established is the mechanism of the charging of the mineral surface. Most researchers have postulated that the adsorption of H⁺ is the cause. However, the adsorption model and its derivatives (such as the amphoteric and multisite-adsorption models), do not successfully describe the data for the zeta potential as a function of pH. In particular, these adsorption models have the following features that are not observed: (i) they are symmetrical about the point of zero charge, whereas the data is asymmetrical, (ii) they have an inflection at the pK_a values, leading to an asymptotic approach to the point of zero charge, whereas such an inflection is not observed, and (iii) they only fit the data in its extremes, that is, when the pK_a values differ by orders of magnitude, or are very close to one another. An alternative mechanism of charging is proposed here that is based on the dissolution of ions from and deposition of ions onto the mineral surface. It is shown that this model (a) fits the data, (b) is consistent with the thermodynamic model for reversible interfaces, (c) is consistent with the thermodynamics of the overall reaction and its solubility, (d) indicates reasons for the ageing of surfaces and (e) displays the observed features of zeta potential measurements as a function of pH, that is, it is pseudo-Nernstian and asymmetrical in nature. Application of the proposed theory is discussed for the flotation of quartz and corundum.     

铜离子在钙基蒙脱石上的吸附解吸行为

吸附去除水溶液中重金属离子是废水处理研究最主要内容之一,而它的工业应用受限于吸附剂的解吸效率。利用动力学及Langmuir等温模型研究了铜离子在钙基蒙脱石上的吸附解吸行为。结果表明:吸附容量和去除率主要受铜离子初始浓度及溶液pH值的影响,当初始浓度为40.84 mg/L且pH6时,99%的铜离子可被蒙脱石吸附去除。吸附过程符合伪二级动力学和Langmuir等温模型,线性相关性均在99%以上,吸附容量的实验值与Langmuir模型计算值相吻合。吸附的铜离子很容易在高浓度的氯化钠溶液中解吸出来,解吸率可达90%。连续4次吸附解吸后蒙脱石仍保持较强的吸附能力,且每次解吸后因层间为更易交换的钠离子,使前两次再生的蒙脱石吸附容量高于首次钙基蒙脱石的吸附容量。利用XRD对吸附及解吸前后的蒙脱石进行表征,结果与上述实验一致。     

新型捕收剂浮选锂辉石的作用机理研究

通过浮选试验、表面张力测试、Zeta电位以及红外光谱分析,考察了油酸钠(NaOL)、脂肪酸甲酯磺酸钠(MES)两种捕收剂及其组合对锂辉石的浮选性能及作用机理。结果表明:单一捕收剂在一定浓度下都能较好的浮选锂辉石,其中MES的捕收性能强于NaOL,组合捕收剂浮选效果明显优于单一捕收剂。捕收剂用量为200 mg/L,NaOL∶MES=5∶1摩尔比组合的浮选效果相对最佳。红外光谱研究表明NaOL在锂辉石表面是以化学吸附为主,MES则是以物理吸附为主,两种捕收剂组合后并没有生成新物质,而是由于锂辉石矿物表面为非均质体,同时不同活性质点间的差异使其具有选择性地吸附在不同位置的矿物表面。     

Ca2+、Mg2+、SO42-、PO43-对晋宁磷矿浮选的影响

浮选过程中多次循环后的选矿废水,其累积的药剂及无机离子达到一定浓度时会影响浮选过程,增加药耗、降低回收率,甚至影响精矿质量。为研究高浓度无机离子对矿物可浮性的影响,以云南晋宁磷矿为研究对象,浮选过程中分别添加Ca2+、Mg2+、SO42-、PO43-进行单因素及正交试验,研究4种离子对磷矿正浮选的影响。结果表明,Ca2+、Mg2+对磷矿正浮选影响较大,当回水中钙镁离子超过100 mg/L时,需去除钙镁离子后选矿废水方能回用。     

NaOH和机械搅拌对锂辉石表面及浮选行为的影响

NaOH和机械搅拌在锂辉石浮选预处理过程中发挥着重要的作用,为了探明其作用机理,开展了锂辉石单矿物和实际矿石浮选试验,进行了X光电子能谱(XPS)和电感耦合等离子体光谱(ICP)检测分析。结果表明,经过3 000mg/L NaOH用量并施以相应时长和速度的搅拌预处理,可使-0.15+0.074mm粒级的锂辉石单矿物回收率提升70%左右;在相同的3 000mg/L NaOH用量下,静置浸泡和施加叶轮线速度3.93m/s的搅拌。检测分析结果表明,固液分离液中的Si离子浓度增大且矿物表面Al和Li原子相对含量均增大;说明锂辉石矿物表面发生了溶蚀现象,且机械搅拌可以促进其表面的溶蚀,暴露更多的金属阳离子为油酸根在锂辉石表面的吸附提供更多的吸附位点;但表面溶蚀后产生的硅酸盐阴离子组分具有较强的亲水性,吸附于矿物表面,致使单矿物可浮性提升而强化机械搅拌后实际矿石浮选试验中Li2O回收率下降。该研究对锂辉石及硅酸盐矿物浮选预处理的研究具有重要的意义。     

The effect of the reagent suite on froth stability in laboratory scale batch flotation tests

In batch flotation tests conducted on ores from the Merensky reef, changes in froth stability invariably occur with variations in the reagent suite. The main reagents are collectors (primary and secondary), activators, depressants and frothers. Since the particles entering and leaving the froth in a batch flotation system are continuously changing, the stability of the froth can vary. Under these conditions the simplest measure of froth stability is the measure of water recovery at a fixed froth height. The batch flotation system developed at UCT allows for the separation of gangue which is entrained relative to gangue which is floated. It has been found that the presence of naturally floatable gangue (NFG) leads to froth stabilisation, whereas the presence of hydrophobic sulfide minerals may lead to destabilisation of the froth depending on the hydrophobicity (contact angle) of the sulfide minerals. This can vary with ore type since particle shape and amount of particles present can influence the extent of destabilisation. At low depressant dosages sodium isobutyl xanthate (SIBX) always results in lower froth stability than sodium ethyl xanthate (SEX). The frothing nature of dithiophosphate leads to increased froth stability and the addition of copper sulfate results in destabilised froths. Increasing depressant dosage reduces the stabilising influence of NFG and the depressant type (guar gum or CMC) also affects froth stability. Frother can be used in an attempt to overcome the destabilising effects of high depressant dosage. This work examines the effect of variations in the reagent suite and uses water recovered at a fixed froth height as an indication of froth stability in order to analyse these effects on the recovery of sulfide minerals, floatable gangue and entrained gangue.     

钙基、钙钠基蒙脱石与亚甲基蓝反应的研究

以浓度、PH和时间为因子研究了浙江横潭、仇山和广西宁明蒙脱石与亚甲基兰（MB）的反应。研究表明，MB_ 聚集于矿物内外表面，并产生二聚物（MB）_2。，陈化时间延长，出现游离MB_ 、三聚物（MB）_3。和高聚物、MBH_2 。氢氧化钠对钙基蒙脱石改性作用较大，增强蒙脱石的吸附活性。     

Effect of amine and starch dosages on the reverse cationic flotation of an iron ore

In iron ore concentration, reverse cationic flotation of quartz has been successfully employed for particles below 150 μm previously deslimed. Amine and starch are used, respectively, as quartz collector and iron oxides depressant. Understanding the mechanisms of reagents interaction is relevant to improve the separation selectivity, especially for high amine dosages. The term clathrate was used to explain this interaction, meaning a molecular compound in which molecules of one species occupy the empty spaces in the lattice of the other species, resulting in the depression of hydrophobic minerals. Laboratory scale experiments were carried out with itabirite iron ore in three different size ranges. The clathrate formation between molecules of amine and starch may explain the increase of SiO₂ content in the concentrates of the coarse size range (−150 + 45 μm) due to an increase in amine dosage.     

改性累托石对水溶液中Zn(II)吸附作用的研究

采用天然累托石粘土,经十二烷基二甲基苄基氯化胺(1227)有机改性后对水溶液中Zn(II)进行了吸附研究。考察了pH值、吸附剂用量、吸附平衡时间等因素对Zn(II)吸附效果的影响。结果表明,吸附最佳条件是:pH为8,吸附剂用量8g/L,吸附平衡时间40min。从吸附等量线和吸附等温线得知,该吸附满足Freundlich吸附机理,在常温下可自发进行,温度升高对吸附不利。     

The flotation behaviour of N-(3-aminopropyl)-dodecanamide on three aluminosilicates

The surface properties and flotation behaviour of aluminosilicates including kaolinite, illite and pyrophyllite, using N-(3-aminopropyl)-dodecanamide as a collector, have been investigated. The best recoveries of kaolinite, illite and pyrophyllite were respectively 91.5%, 90.6%, and 96.3%. On the basis of FT-IR spectra and zeta potential, the ionization of surface hydroxyl, as well as isomorphic exchange of surface ions, accounts for the mineral surface charges. The mechanisms of interactions of the mineral surface with collectors depend on the pH of the pulp. In the acidic region, the interactions of the mineral surfaces with the collector were mainly electrostatic, but in the alkaline region, the interactions are mainly due to hydrogen bonding. It can be seen from SEM photographs of aluminosilicates that pyrophyllite takes the shape of thin slices, but kaolinite and illite have irregular porous structures. Specific surface area and particle size distributions of aluminosilicates also indicate that kaolinite and illite are relatively large porous particles with larger external as well as internal surface areas.     

The effect of stirring speed and induction time on flotation

A computational fluid dynamic model has been developed for a modified Denver flotation cell used in laboratory batch tests. The model incorporates fundamental aspects of bubble-particle interactions including bubble-particle collision, attachment and detachment. Model predictions are compared against carefully planned laboratory experiments with narrowly-sized spherical ballotini. Flotation results for different impeller speeds have been obtained for a constant air flow into the cell. The particles have been made hydrophobic by methylation with trimethylchlorosilane. For a given particle size, the results from the model and experimental work indicate that there is an optimum stirring speed that produces a good compromise between attachment and detachment rates in the cell for flotation. For less hydrophobic particles, a lower stirring speed is beneficial in having a longer contact time because of the longer induction time required for attachment.     

Influence of important factors on flotation of zinc oxide mineral using cationic, anionic and mixed (cationic/anionic) collectors

In this study, the influences of important factors on smithsonite flotation are investigated. Dosages of sulphidizing agent and collector, desliming prior to flotation and the use of sodium hydroxide instead of sodium carbonate as the pH regulator are essential to the effective recovery of smithsonite in cationic flotation. The appropriate temperature for flotation was found to be 30–40 °C. Sodium hexametaphosphate (SH) and sodium silicate had the greatest selectivity between smithsonite–calcite and smithsonite–quartz, respectively. The results of oleic acid flotation showed that the grade and recovery of zinc were relatively low in comparison with the sulphidization-cationic flotation method. Despite using sodium silicate and SH as depressants in oleic acid flotation, flotation was not selective. Flotation using mixed collectors (Armac C + Potassium Amyl xanthate) showed promising results. The ratio of the mixed collectors and the sequence of addition of mixed collectors were important criteria in attaining true mixed collector flotation.     

铁介质磨矿对锂辉石和绿柱石浮选影响的分子模拟计算研究

利用分子模拟计算方法,研究了铁球作为磨矿介质,十二胺和油酸钠分别作为捕收剂,锂辉石和绿柱石与捕收剂在磨矿前后的相互作用能。结果表明,这两种典型硅酸盐矿物经过铁球磨矿后,矿物表面吸附的铁,使阳离子捕收剂十二胺与矿物的相互作用能增大,阴离子捕收剂油酸钠与矿物的相互作用能减小,进而影响捕收剂与矿物之间的相互作用。总体来讲,锂辉石和绿柱石经过铁球磨矿后,一般会阻止十二胺阳离子捕收剂在矿物表面的吸附,而对于油酸根阴离子捕收剂,则起到一定的活化作用,有利于油酸根离子在矿物表面的吸附。     

Investigation of gas dispersion characteristics in stirred tank and flotation cell using a corrected CFD-PBM quadrature-based moment method approach

In this study, the population balance model (PBM) is coupled with computational fluid dynamics (CFD) to investigate the steady-state bubble size distribution in two types of process equipment namely, a standard Rushton turbine stirred tank reactor and a generic lab-scale flotation cell. The coupling is realized using Fluent 15.07 software, and the numerical model is validated for the stirred tank reactor. The population balance equation (PBE) is solved using the quadrature method of moments (QMOM) technique along with a correction procedure implemented to check and correct invalid moment sets. The breakage and coalescence of bubbles due to turbulence are considered. The breakage rate and daughter size distribution models proposed by Laakkonen et al. (2007) are considered. For modeling coalescence rate, models proposed by Coulaloglou and Tavlarides (1977) are considered. The interaction between the phases is handled by considering the drag model proposed by Lane et al. (2005) while ignoring the other interphase forces. The correction algorithm has been successfully implemented, and improved predictions of gas volume fraction and Sauter mean diameter (SMD, d₃₂) have been observed with a good match between the predictions and experimental measurements. The local SMD predictions are compared against predictions from the past studies and the superiority of the current approach for moderate gassing rates is established. The CFD-PBM approach is then used to study and characterize different flow regimes occurring in a generic mechanical flotation cell at different aeration rates and impeller rotation speeds. Also, power numbers are calculated from torque data and are found to drop considerably with an increase in aeration rate and impeller rotation speed as the flow regime approaches recirculating flow. The predicted SMD for flotation cell indicates that smaller bubbles are concentrated near the high turbulence impeller stream, the lower recirculation region, and close to the tank walls. On the other hand, large bubbles are formed in the upper tank region and are concentrated around the shaft during the flooding, loading, and transition flow regimes. In the future, the corrected QMOM approach will be further extended by implementing kinetic models capable of predicting the flotation rate constant using local bubble size information obtained from CFD-PBM simulations.     

Evaluation of equilibrium, kinetic and thermodynamic parameters for biosorption of nickel(II) ions onto bacteria strain, Rhodococcus opacus

The present study explores the ability of Rhodococcus opacus bacteria strain for the removal of nickel(II) under different experimental conditions. The effects of relevant parameters such as solution pH, biomass loading, ionic strength, and temperature on nickel(II) biosorption capacity were evaluated. Although the tests were carried out using synthetic solutions, the results are representative of typical waste effluents from chemical, dyestuffs, battery manufacture, porcelain enameling, metallurgical industries and electroplating circuits. The sorption data followed the Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Sips isotherms. The maximum sorption capacity was found to be 7.63 mg g⁻¹ at pH 5. Thermodynamic parameters have also been evaluated and the results show that the sorption process was spontaneous and endothermic in nature. The dynamics of the sorption process were studied and the values of rate constants for different kinetic models were calculated. The activation energy of biosorption (E_a) was determined as 12.56 kJ mol⁻¹ using the Arrhenius equation.