Bubble attachment time and FTIR analysis of water structure in the flotation of sylvite, bischofite and carnallite

Water structure is the most important parameter that influences the flotation of soluble salts. In this paper bubble attachment time measurements and FTIR analyses were performed to investigate the effect of water structure on the flotation behavior of sylvite (KCl), bischofite (MgCl₂·6H₂O) and carnallite (KMgCl₃·6H₂O). The results from bubble attachment time measurements suggest that collector adsorption at the surface of KCl induces flotation with either the cationic collector, ODA, or anionic collector, SDS. In contrast bubble attachment did not occur for bischofite (MgCl₂·6H₂O) or carnallite (KMgCl₃·6H₂O). Results show that the surface charge is not a determining factor in the flotation of soluble salts.Further, the interaction between water molecules and the three chloride salts dissolved in aqueous solution were studied by measuring the shift in the hydrogen-bonding of water molecules. The results indicate that KCl is a structure breaker salt, while MgCl₂·6H₂O and KMgCl₃·6H₂O are structure maker salts.Viscosities for the brines of these three salts were determined. The results give additional evidence of differences in water structure and are in good agreement with the FTIR and bubble attachment results. The findings provide further evidence that water structure plays an important role in the flotation of soluble salts.     

Critical coalescence concentration of inorganic salt solutions

Critical coalescence concentration (CCC) was determined in a laboratory-scale mechanical flotation cell for a series of coalescence inhibiting inorganic salts (KCl, NaCl, Na₂SO₄, CaCl₂ and MgSO₄) compared to two commercial frothers (methyl isobutyl carbinol, Dowfroth 250C). The salt CCC values ranged from 0.07 M (MgSO₄) to 0.31 M (KCl and NaCl) and correlated with ionic strength. The CCC values are compared to transition concentrations in the literature. The effect of salts on gas dispersion in flotation systems is discussed.     

Potash flotation practice for carnallite resources in the Qinghai Province,PRC

Two potash plants at the Qarhan Salt Lake in Qinghai Province, Peoples Republic of China, were visited in July 2012 to discuss processing strategies, particularly flotation technology. The first plant, operated by Qinghai Avic Resources Co., Ltd., in Mahai, is using the traditional KCl flotation from NaCl with an amine as collector after selective decomposition of carnallite (KCl.MgCl₂⋅6H₂O). The second plant is operated by the Qinghai Salt Lake Group in Geermu where NaCl is floated from carnallite with an alkyl-morpholine as collector prior to carnallite decomposition for KCl production. These two major potash flotation technologies being used in the Qinghai Province of the Peoples Republic of China are reviewed and discussed with respect to recent research findings regarding the use of alkyl-morpholine collectors in reverse flotation of NaCl from carnallite.     

Contact angle and bubble attachment studies in the flotation of trona and other soluble carbonate salts

Trona, Na₂CO₃ · NaHCO₃ · 2H₂O, is mined as the primary source for sodium carbonate production in the United States. Recent studies have shown that the flotation method can be used for pre-processing of trona ore to remove insoluble mineral contaminants for the production of soda ash (sodium carbonate). Studies with carbonate salts suggest that certain important factors can affect their flotation response, including viscosity of the brine and interfacial water structure. Flotation studies showed that contrary to the strong flotation of NaHCO₃ with both anionic and cationic collectors, Na₂CO₃ does not float at all. Based on the analysis of interfacial water structure in saturated brines, Na₂CO₃ was found to act as a strong water structure maker, whereas NaHCO₃ acts as a weak water structure maker. Bubble attachment time measurements suggest that collector adsorption at the surface of NaHCO₃ induces flotation; this is not the case for Na₂CO₃. Contact angle measurements indicated that the surface of Na₂CO₃ is hydrated to a great extent, whereas the NaHCO₃ salt surface is less hydrated. These results reveal that there is a strong relationship between the interfacial water structure and the contact angle of these salts. The less stable NaHCO₃ surface is ascribed to the interfacial water structure which allows for NaHCO₃ flotation with both anionic and cationic collectors.     

从选钼尾矿中回收制钾肥长石选矿试验研究

黑龙江某大型钼矿选钼尾矿K2O品位为6.91%,Na2O品位为1.79%,经过试验研究采用脱泥-浮选除杂-长石浮选-强磁选除杂的工艺流程,选钼尾矿脱泥后采用油酸钠浮选除杂,然后添加硫酸调整pH值至3.6,采用BK440作长石捕收剂浮选分离长石与石英,长石浮选精矿在15000kA/m场强下脱除磁性矿物,获得长石精矿K2O品位为11.54%, Na2O品位为2.51%,K2O回收率为47.73%;Na2O回收率为40.30%。长石精矿达到制钾肥钾长石质量标准。     

Acid leaching of metals from deep-sea manganese nodules – A critical review of fundamentals and applications

The mass% metal composition of deep sea nodules ranges from 10–28% Mn, 4–16% Fe, 0.3–1.6% Ni, 0.02–0.4% Co, and 0.1–1.8% Cu in mixed oxide matrices with alumina and silica. The concentrations of base metal ions in sea water of pH ∼ 8 of the order 10⁻³–10² nmol/kg are shown to be dependent on the solubility products (K_SP) of carbonate sediments. Cations of higher softness have higher pK_SP and lower solubility. Previously reported leach results of nodules in H₂SO₄ and HCl under atmospheric pressure and temperatures in the range 30–90 °C and in the absence or presence of SO₂, Na₂SO₃, NaCl and CaCl₂ are used in the present study to compare, contrast and rationalise the leaching behaviour of metal values. Leach efficiency of metals increases with increasing acid concentration, and Cu(II) and Zn(II) follow the same trend in HCl. Potential–pH diagrams of base metal oxides show a higher stability of mixed metal oxides such as ferrites, magnetite and manganite, which causes partial dissolution of high-valent oxides in the absence of reducing agents. Application of a shrinking core kinetic model in both H₂SO₄ and HCl media predicts a proton diffusivity of ∼ 10⁻¹¹ cm² s⁻¹ for the dissolution of Ni from nodules. This value is of the same order as D_H⁺ for the high pressure acid leaching of Ni from limonitic laterite. A linear correlation between leaching efficiencies of Fe and Ni appears to be a result of co-dissolution of these metals from NiO·Fe₂O₃ or NiFeOOH. The first order dependence of initial dissolution rates of Cu(II) with respect to H⁺ concentration in H₂SO₄, and the beneficial effect of background chloride ions, suggests a dissolution mechanism: CuO → Cu(OH)Cl_ads/aq → CuSO₄. The Cu(II) ions in solution can also affect Ni(II) dissolution from oxide by cation exchange mechanism. The presence of SO₂ or Na₂SO₃ as reducing agents facilitates the acid leaching of high-valent oxides of Mn and Co and other metals incorporated in the mixed oxide matrix. Whilst Fe(II) ions formed during the reductive leaching of Fe(III)-oxides accelerate the dissolution of Mn(III)/(IV) oxides, the resultant Mn(II) ions accelerate the dissolution of high-valent Co-oxides. Leaching efficiency in HCl increases with temperature. As for the SO₂/H₂O system thermodynamic calculations predict a decrease in concentration of H⁺ and at high temperatures, which retards leaching efficiency. The SO₂/H₂O/air leach system enhances metal dissolution due to the production of H₂SO₄ via the transition metal catalysed oxidation of SO₂ to H₂SO₄.     

Purification of rare earth elements from monazite sulphuric acid leach liquor and the production of high-purity ceric oxide

The present work describes the development of an efficient and relatively simple process to obtain high grade CeO₂ from sulphuric acid leach liquor. The liquor was obtained through acid digestion of monazite. The steps investigated in the process for obtaining ceric oxide were: (i) purification of the RE elements through their precipitation as rare earth and sodium double sulphate (NaRE(SO₄)₂·xH₂O), (ii) NaRE(SO₄)₂·xH₂O conversion into RE-hydroxide (RE(OH)₃) through metathetic reaction and (iii) recovery of cerium and (iv) purification of cerium from the mixture of ceric hydroxide and manganese dioxide precipitate through dissolution of the solid with HCl and precipitation of the cerium through the addition of oxalic acid (H₂C₂O₄) or ammonium hydroxide (NH₄OH) solution. The X-ray diffraction spectra of the double sulphate obtained indicated the presence of monohydrated double sulphate. X-ray diffraction and chemical analysis indicated that the precipitation should be carried out at 70 °C and at 1.1 times the stoichiometric ratio of NaOH. An excess of 30% of KMnO₄ was necessary to separate cerium from the other RE elements. Both oxalic acid and ammonium hydroxide proved efficient in the precipitation of cerium from the mixture of Ce/Mn obtained in the cerium separation. Following purification, calcinated products were obtained, assaying between 99% and 99.5% CeO₂. The cerium recovery yield was greater than 98%.     

Upgrading of a chalcopyrite concentrate by reaction with copper(II) and sulfite – Unexpected formation of Chevreul’s salt,Cu2SO3·CuSO3·2H2O

Recovery of aqueous copper(II) onto a chalcopyrite concentrate was shown to be rapid at 60 °C in the presence of S(IV), in this case sulfite. Surprisingly, rather than partial conversion of chalcopyrite to a copper sulfide such as chalcocite or covellite, copper was removed from solution by precipitation of a mixed-valence copper sulfite, Chevreul’s salt (Cu₂SO₃·CuSO₃·2H₂O). This has application as a way to increase the copper grade of chalcopyrite concentrates using the leachate from a Galvanox? leach of flotation tailings, offering several advantages over similar processes employing an autoclave to effect copper precipitation.     

扩散渗析法对镍电积阳极液酸盐分离应用试验研究金川集团股份有限公司,雷军鹏 郑军福 卫媛

本文针对含酸电积阳极液需在生产过程中平衡中和的生产实际,采用扩散渗析膜法对电积阳极液中的硫酸和硫酸镍溶液进行了分离研究。结果表明,通过扩散渗析,硫酸回收率在80%以上,镍的截留率在90%以上。在接受液分别为自来水和碳酸镍上清液的情况下,扩散渗析法能有效回收硫酸同时对镍离子具有较好的拦截性能。     

Salt-tolerant microorganisms potentially useful for bioleaching operations where fresh water is scarce

Anions and cations can accumulate in process waters due to the source water, to evaporation and because of gangue mineral dissolution. Common salts that can accumulate from mineral gangues are the anions, chloride and sulfate, both of which impact on microorganisms used in bioleaching processes. The search for salt-tolerant acidophilic microorganisms able to tolerate high concentrations of these salts, as well as high concentrations of metals, has been underway for at least 20 years because their application would considerably improve bioleaching process efficiency in areas where fresh water is scarce.A thorough search of microorganisms from saline and acidic drains, lakes and sediments in the South West of Western Australia and a CSIRO culture collection was undertaken to bio-prospect for salt-tolerant bioleaching cultures. Pure strains of common bioleaching acidophiles did not tolerate seawater salinities, however, enrichment cultures of mesophilic acidophilic microorganisms that could tolerate up to 70 g/L sea salts and 350 g/L MgSO₄⋅7H₂O were established. The salt tolerance of acidophiles was less in thermophilic temperature ranges, compared with mesophilic and moderately thermophilic temperature ranges. Tolerance to sulfate salts was greater than chloride with magnesium ions likely limiting maximum sulfate tolerance. Iron oxidising cultures were more sensitive than sulfur oxidising cultures to higher chloride concentrations. The addition of pyrite to enrichment cultures increased salt tolerance. The efficacy of the salt tolerant cultures to extract copper will be determined in bioleaching experiments with chalcopyrite ore and salty process water.     

含钒石煤选择性脱泥富集钒的试验研究

含钒石煤,经焙烧脱碳后,在磨矿过程中会产生大量的原生及次生矿泥,这些矿泥的存在,在浮选过程中会消耗大量浮选药剂,增加选矿成本,并降低选矿指标。针对湖北通山含钒石煤进行了选择性脱泥富集钒的试验研究,在用20%H2SO4溶液调节p H为9.0,六偏磷酸钠的用量为1.0 kg/t条件下,得到了V2O5的品位为1.07%,产率为10.91%的矿泥产品。     

Hydrotalcite Formation for Contaminant Removal from Ranger Mine Process Water

Process water from the Ranger Uranium Mine requires treatment to meet stringent environmental water quality criteria. The acidic water contains substantial SO₄, metals, and U. One novel treatment method under consideration is the use of Na-aluminate to both neutralise the process water and precipitate hydrotalcites. Hydrotalcites are a class of Mg–Al layered double hydroxide minerals with a typical endmember chemical composition: Mg₆Al₂(A)(OH)₁₆·n(H₂O), where A = CO₃ ²⁻, SO₄ ²⁻, etc. Many acidic wastewaters contain Mg and/or Al in sufficient abundance for hydrotalcite formation upon addition of alkali to achieve solution pH > 5, and Mg and/or Al to attain a Mg:Al ratio of 2 to 3:1. The utility of hydrotalcites lies in their ability to incorporate a range of cationic (Cu²⁺, UO₂ ²⁺), metalloid (AsO₄ ³⁻), and (oxy)anionic contaminants (CrO₄ ²⁻). The broad spectrum removal of contaminants, including U, also indicates that hydrotalcites and their derivatives could potentially be used as a containment material in nuclear waste repositories. In this study, Ranger process water derived from extraction of U from chloritic schist was treated with Na-aluminate sourced from Bayer process liquor, in combination with NaOH or Ca(OH)₂. Hydrotalcites formed as the primary mineral during process water neutralisation with the ability to simultaneously remove a suite of contaminants from solution.     

Surface properties of enargite in MAA depressant solutions

Enargite (Cu₃AsS₄) is a common penalty mineral in the copper mining industry. Different treatment methods have been proposed to passivate the enargite surface for effective flotation of non-arsenic copper minerals, including pulp potential control, pre-oxidation and chemical depression. Magnesium ammonium mixture (MAA) has been previously tested, showing good selectivity for arsenic rejection. It was hypothesised that MAA would make the enargite surface hydrophilic by adsorption of magnesium ammonium arsenate hexahydrate (MgNH₄AsO₄·6H₂O). Here we show that MAA does not selectively adsorb onto the enargite surface as conjectured. X-ray photoelectron spectroscopy and cyclic voltammetry show that magnesium compounds do not precipitate onto the enargite surface at pH 10, whereas magnesium hydroxide on the enargite surface is formed at pH 12. MgNH₄AsO₄·6H₂O was not observed at either pH 10 or pH 12. The effect of pre-oxidation to promote dissolution of (AsO₄)³⁻ before conditioning with MAA, which could help catalyse the formation of MgNH₄AsO₄·6H₂O, was also tested. However, the results were the same as those without pre-oxidising the sample. Our investigation shows that under alkaline conditions it is not possible to passivate the enargite surface in MAA solutions for effective flotation of non-arsenic copper minerals.     

黄金工业高盐度废水的处理研究

通过超滤装置的预处理,除去高盐度废水中的胶体和悬浮物。然后通过一级纳滤装置将 进行浓缩,浓缩液通过冷冻系统将K₂SO₄进行回收;一级纳滤装置出水经过二级纳滤装置处理后,出水回用到生产车间,二级纳滤装置的浓缩液重新回到超滤装置。高盐度废水经过处理后,其中的K₂SO₄得到了回收,废水基本达到零排放,可以实现良好的经济效益和社会效益。     

Preparation of high-purity and low-sulphur graphite from Woxna fine graphite concentrate by alkali roasting

An alkali roasting process, which consists of roasting with caustic soda, water washing and sulphuric acid leaching, has been found to be an effective method for graphite purification even at low roasting temperature. With this process, a flotation fine concentrate containing 87–88% carbon could be purified to about 99.4% carbon when roasted with 25% NaOH at 250 °C and leached by 10% H₂SO₄ solution at room temperature. In addition to the successful removal of silicate impurities, the process was also found to be effective to eliminate sulphide impurities. For instance, the sulphur content in the end product could be reduced to below 0.05% from 0.6% by the process. Furthermore, the consumption of NaOH can be lowered by using high-grade feed. When using a feed of 95.9% carbon (upgraded by flotation), the NaOH concentration could be reduced to 10% from 25% while the product purity could reach the same purity level of over 99%.     

Mine Water as a Resource: Selective Removal and Recovery of Trace Antimony from Mine-Impacted Water

The objective of this study was to evaluate the feasibility of combined modular processes to selectively remove Sb from mine-impacted waters in an Arctic environment in order to fulfil local environmental criteria for discharged waters. Novel ion exchange, selective extraction and ultrafiltration, electrocoagulation, and dissolved air flotation technologies were investigated, individually or in combination, from the laboratory- to pilot-demonstration scale. Laboratory-scale testing using Fe₂(SO₄)₃ precipitation, ion exchange resin, selective ion extraction and ultrafiltration, and electrocoagulation with or without subsequent dissolved air flotation indicated that any of the methods are potentially applicable to Sb removal from mine water. The observed differences between Sb and As removal efficiency by ion exchange resin illustrated the need for Sb-specific removal and recovery technologies. Techno-economic analyses showed that treatment of mine water using electrocoagulation-dissolved air flotation yields the lowest comparative life-cycle cost of examined technologies. Results demonstrated increased Sb attenuation efficiency using either electrocoagulation-dissolved air flotation or selective extraction and ultrafiltration, even when treating only 50% of the mine-impacted water, compared with conventional Fe₂(SO₄)₃ precipitation from mine water. Additional investigation is necessary to characterize the long-term stability of the mineral phases in Sb-containing solid residues and to inform selection of Sb recovery methods and utilisation or final disposal options for the residual materials.

     

Recovery of feldspar from trachyte by flotation

In this study, recovery of feldspar from trachyte by flotation was studied. A feldspar concentrate containing 5.72% K₂O, 5.33% Na₂O, 0.321% Fe₂O₃ and 0.080% TiO₂ was obtained from a feed containing 5.20% K₂O, 3.37% Na₂O, 1.778% Fe₂O₃ and 0.253% TiO₂ with an overall recovery of 22.4% by weight.     

Effect of thermal stability on the flotation response of sodium carbonate salts

Laboratory microflotation experiments show that flotation of certain sodium carbonate salts with cationic and anionic collectors is possible if the salts are thermodynamically stable under the prevailing experimental conditions. Sodium carbonate monohydrate can be floated up to 100% recovery with cationic dodecyl amine hydrochloride (DAH) and anionic sodium dodecyl sulfate (SDS) collectors at temperatures above 40 °C. Sodium carbonate decahydrate floats to a maximum yield of about 30% with 1×10⁻³ M DAH and to 17% with 1×10⁻⁴ M SDS even at room temperature where it is thermodynamically stable. Trona, the double salt of sodium carbonate and bicarbonate, does not float at room temperature in its saturated solution with either collector. Complete flotation of sodium bicarbonate in its saturated solution at pH 8.3 occurs with both DAH and SDS at all temperatures. Complementary data on flotation, viscosity and FTIR studies reveal that in addition to the thermal stability, the flotation response is dictated by the relative contributions of viscosity and water structuring properties of soluble carbonate salts.     

某硫铁烧渣浮选脱硫试验研究

重庆某硫酸厂硫铁烧渣硫含量高达5.79%,为了生产铁精矿,需要将硫含量降低至1.5%以下。试验在控制磨矿细度为-0.074mm占86%的条件下,以硫酸铜加硫酸为活化剂,丁基黄药为捕收剂,2#油作起泡剂,通过一粗二精的反浮选流程,使硫品位降低至1.32%。浮选精矿再经磁选,得到精矿S品位0.81%,Fe品位60.25%,回收率82.45%的良好指标。     

Pyromorphite : Bunker Hill Mine,Coeur d'Alene District,Shoshone County,Idaho

Nikischerite, ideally NaFe²⁺ ₆Al₃(SO₄)₂(OH)₁₈(H₂O)₁₂, occurs as dark yellow-green micaceous plates to 4 mm, forming radiating balls and aggregates (Huminicki et al. 2003). The mineral has a dull to greasy luster, a pale grayish streak, and a Mohs hardness of 2. It has a perfect cleavage parallel to {001}, which is also the dominant form displayed by the platy crystals. The type locality is the Huanuni tin mine, Dalence Province, Oruro Department, Bolivia, where nikischerite occurs in and on a clay matrix, associated with minor pyrite, pyrrhotite, siderite, and cronstedtite.