Oxidation of Fe(II) in a synthetic nickel laterite leach liquor with SO2/air

Under specific controlled conditions, the addition of SO₂ to oxygen or air produces the peroxy-monosulphate free radical in solution, which is a stronger oxidant than oxygen alone. In this study, the practical strategies required to optimise the oxidation of Fe(II) with SO₂/air was investigated at 75 °C as part of a process to remove iron as Fe(III) oxides from a synthetic nickel laterite high pressure acid leach solution containing 5 g/L Fe(II), 1 g/L Fe(III), 8 g/L Ni, 30 g/L Mg in sea water at pH about 2. The rate of Fe(II) oxidation was optimised in the pH range of 1.2–2.0 with respect to SO₂/air ratio and gas flow rates for minimum production of H₂SO₄ and maximum utilisation of SO₂. In order to minimise the air flow rates into the reactor vessel, the maximum rate of SO₂ addition that could be employed with air was established whilst maintaining oxidising conditions. The results provide strategies for commercial applications of the SO₂/air oxidising system and indicate important factors for reactor design.     

Downflow Limestone Beds for Treatment of Net-Acidic, Oxic, Iron-Laden Drainage from a Flooded Anthracite Mine, Pennsylvania, USA: 2. Laboratory Evaluation

Acidic mine drainage (AMD) containing elevated concentrations of dissolved iron and other metals can be neutralized to varying degrees by reactions with limestone in passive treatment systems. We evaluated the chemical and mineralogical characteristics and the effectiveness of calcitic and dolomitic limestone for the neutralization of net-acidic, oxic, iron-laden AMD from a flooded anthracite mine. The calcitic limestone, with CaCO₃ and MgCO₃ contents of 99.8 and <0.1 wt%, respectively, and the dolomitic limestone, with CaCO₃ and MgCO₃ contents of 60.3 and 40.2 wt%, were used to construct a downflow treatment system in 2003 at the Bell Mine, a large source of AMD and baseflow to the Schuylkill River in the Southern Anthracite Coalfield, in east-central Pennsylvania. In the winter of 2002–2003, laboratory neutralization-rate experiments evaluated the evolution of effluent quality during 2 weeks of continuous contact between AMD from the Bell Mine and the crushed calcitic or dolomitic limestone in closed, collapsible containers (cubitainers). The cubitainer tests showed that: (1) net-alkaline effluent could be achieved with detention times greater than 3 h, (2) effluent alkalinities and associated dissolution rates were equivalent for uncoated and Fe(OH)₃-coated calcitic limestone, and (3) effluent alkalinities and associated dissolution rates for dolomitic limestone were about half those for calcitic limestone. The dissolution rate data for the cubitainer tests were used with data on the volume of effuent and surface area of limestone in the treatment system at the Bell Mine to evaluate the water-quality data for the first 1.5 years of operation of the treatment system. These rate models supported the interpretation of field results and indicated that treatment benefits were derived mainly from the dissolution of calcitic limestone, despite a greater quantity of dolomitic limestone within the treatment system. The dissolution-rate models were extrapolated on a decadal scale to indicate the expected decreases in the mass of limestone and associated alkalinities resulting from the long-term reaction of AMD with the treatment substrate. The models indicated the calcitic limestone would need to be replenished approaching the 5-year anniversary of treatment operations to maintain net-alkaline effluent quality.     

纳米级(W,Ni,Fe)复合氧化物粉末的制备

通过适当的溶液配制，并采用喷雾干燥法制备了（W，Ni，Fe)复合氧化物粉末。对复合氧化物粉末进行煅烧、超声分散得到纳米级(W，Ni，Fe)复合氧化物粉末；使用X射线衍射仪及扫描电子显微镜分别对不同煅烧温度处理的复合氧化物粉末进行了物相分析和形貌观察。研究结果表明：喷雾干燥法制得的复合氧化物粉末各种组元是在原子水平上的均匀混合，且非晶化程度高；400℃煅烧处理后粉末颗粒中各组元还是处于非晶化状态；600℃煅烧处理后，粉末颗粒物相的主要存在形式为WO3(单斜系)、WO3(六方系)和NiWO4；复合粉末BET粒度为80．1nm，复合粉末Fsss粒度为0．42μm；粉末颗粒为球形或近球形，粉末分散性好。     

Selective pressure leaching of Fe (II)-rich limonitic laterite ores from Indonesia using nitric acid

The selective extraction of nickel and cobalt over iron from an Indonesian limonitic laterite was investigated using nitric acid pressure leaching (NAPL). The mineralogical analysis showed that the major minerals were goethite and magnetite, and the content of the divalent iron was as high as 7.06%. Nickel and cobalt were mainly distributed in these two minerals; however, the distribution was non-uniform. A series experiments were conducted to examine the basic parameters and propose the optimal conditions for the extraction. When the ore was treated via HPAL under the optimal condition, the extracted nickel and cobalt were less than 75%, and the iron concentration in the leach liquor was over 12.5 g/L. By contrast, over 85% of nickel and cobalt were extracted and about 1.8 g/L iron was achieved using NAPL. The loss of nickel and cobalt can be mainly attributed to the undissolved magnetite and manganese minerals. The leaching process of NAPL is a dissolution–oxidation–precipitation mechanism, and in this process nitric acid acts as both a lixiviant and an oxidant. The formation of hematite results in a low iron concentration in the leach liquor without oxygen injected. Meanwhile, the oxidation and the precipitation of dissolved divalent iron results in a calculated savings in acid consumption of about 120 kg nitric acid per ton of ore can be obtained, which is equal to over 93 kg of sulfuric acid per ton of ore. Moreover, lower residual acid (20 g/L nitric acid) is a significant advantage of NAPL. The iron residues had a high iron content (>56 wt%) with no sulfur, making it suitable as raw materials for ironmaking.     

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.     

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.     

Biosorption of Cu(II) and Pb(II) from aqueous solutions by dried activated sludge

The biosorption of Cu(II) and Pb(II) ions from aqueous solutions by dried activated sludge was investigated as a function of initial pH, initial metal ion concentration and temperature. The results showed that both the heavy metals uptake processes followed the pseudo-second-order equation. The equilibrium data fitted very well to both Langmuir and Freundlich adsorption models. The main mechanism of Cu(II) and Pb(II) biosorption on dried activated sludge was their binding with amide I group.     

SO2-空气法从钴溶液中除铁、锰的试验研究

采用SO2-空气氧化沉淀法对刚果某铜钴矿浸出液中除铁、锰的工艺进行了试验研究,探讨了过程中各条件因素对氧化沉淀的影响规律。结果表明,在温度30℃,pH 3.5,混合气中SO2浓度2%的最佳工艺条件下,1 h内铁即氧化沉淀完全,而锰的氧化沉淀速率则相对较慢,6 h才达61.7%。除铁后液用碳酸钠沉淀可获得含Co>42%的粗制碳酸钴产品,可直接出售或进一步提纯钴。     

Adsorption of Pb(II), Zn(II) and Cr(III) on coal fly ash porous pellets

In the present work the application of fly ash porous pellets as adsorbent of lead(II), zinc(II) and chromium(III) ions from aqueous solution was studied. Experiments were carried out using porous pellets developed from fly ash derived from Megalopolis, Greece coal-burning power plant. The material was shaped into spherical agglomerates, after wetting and tumbling in a laboratory scale granulator. The adsorption of heavy metals on fly ash pellets was studied as a function of the initial metal concentration, solution pH and temperature. Kinetic studies indicated that sorption follows a pseudo-second-order model. Adsorption isotherms of lead, zinc and chromium were determined for agglomerated material using the Langmuir equation. The adsorption capacity of fly ash pellets reached at 0.22 mmol Pb/g pellet, 0.27 mmol Zn/g pellet and 0.44 mmol Cr/g pellet. Furthermore adsorption from bimetallic solutions (Cr–Zn, Cr–Pb and Pb–Zn) took place in order to study presumable antagonistic effects on adsorption of heavy metals. Finally, the stabilization of metal saturated pellets was studied. The stabilization procedure took place in structures made of concrete, where 75% of cement was replaced by raw fly ash. The evaluation of the procedure through leaching tests showed excellent heavy metals stabilization in concrete blocks.     

Copper(II) uptake by Pleurotus mutilus biomass,chitin and chitosan

Various treated forms of dead Pleurotus mutilus biomass, chitin and chitosan were used for the removal of Cu(II) ions from aqueous solutions. The biomass was found to be as efficient as chitin and maximum yield was obtained at pH around 6. The yield was increased significantly with respect to the free matter when treatments with 0.2% glutaraldehyde or 5% NaOH were perfomed, 23, 42 and 30 mg/g of dry matter respectively being obtained after 60 min equilibrium time. In multi-component solutions containing Cd(II) and Zn(II) the binding capacity toward Cu(II) was reduced.     

The effects of Ca(II) and Mg(II) ions on the flotation of spodumene using NaOL

The effects of Ca(II) and Mg(II) ions on the flotation of spodumene using sodium oleate (NaOL) as the collector were investigated by micro-flotation tests, zeta-potential measurements, absorption measurements, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses. The micro-flotation results indicated that the pH value has a significant influence on the activation of spodumene minerals by Ca(II) and Mg(II) ions. Good floatability of spodumene was obtained with Ca(II) and Mg(II) ions at a pH of 12.5 and 10.0, respectively. In strongly alkaline solutions, Ca(II) and Mg(II) ions readily form hydroxy complexes (CaOH(I) and MgOH(I)) and precipitates (Ca(OH)₂ and Mg(OH)₂). FT-IR and XPS analyses revealed that the hydroxy complexes and the precipitates adsorbed onto the spodumene surface. These species contributed to the formation of oleate complexes and thus increased the amount of collector adsorption and the floatability of spodumene.     

Complexation of Ni(II) by Dimethylglyoxime for Rapid Removal and Monitoring of Ni(II) in Water

The complexation of Ni(II) with dimethylglyoxime (DMG) entrapped within a Nafion membrane and a DMG–sol–gel matrix was studied and compared for different solutions. First and pseudo-second order kinetic models, Elovich, intra-particle, and liquid film diffusion models were applied to evaluate sorption kinetics. Complexation of Ni(II) by DMG entrapped in the polymeric materials followed a pseudo-second order kinetic model; moreover, DMG in Nafion also allowed diffusion-controlled uptake. The pseudo-second order rate constant was significantly higher for the free ligand in solution than for Ni(II) accumulation in the surface-attached DMG-Nafion. The DMG–sol–gel removal ability of Ni(II) was tested using actual mine water. The presence of interferences only insignificantly decreased the removal percentage of Ni(II), thus confirming the high selectivity of DMG towards Ni(II). Also, an electrochemical sensor modified with DMG in Nafion was investigated further for direct electrochemical determination of Ni(II) in untreated mine water. Determination errors and interference effects were low. Thus, this approach represents an effective potential solution for selective Ni(II) removal from mine water as well as a rapid and cheap sensor for on-site monitoring of Ni(II) in mine and environmental waters.     

EDTA二钠去除Cu(Ⅱ)和Ni(Ⅱ)离子对蛇纹石的浮选活化作用

以蛇纹石纯矿物为研究对象,进行了纯矿物浮选、捕收剂(丁基钾黄药)吸附量测定以及相关体系的溶液化学计算分析。结果表明:当pH6时,Cu(Ⅱ)、Ni(Ⅱ)能够有效的活化丁基钾黄药对蛇纹石的浮选捕收,EDTA二钠能够有效去除Cu(Ⅱ)、Ni(Ⅱ)的活化作用;丁基钾黄药几乎不在纯净的蛇纹石表面吸附,Cu(Ⅱ)、Ni(Ⅱ)的存在能够大幅度提高丁基钾黄药在蛇纹石表面的吸附量,EDTA二钠则能有效地降低其吸附量;在pH 9~10的范围内,Cu(Ⅱ)、Ni(Ⅱ)主要以Cu(OH)_2(s)和Ni(OH)_2(s)的形式存在,通过沉淀罩盖活化蛇纹石的浮选;EDTA二钠能够有效地络合稳定矿浆中的铜、镍羟基络合物,从而抑制丁基钾黄药对蛇纹石的浮选捕收。     

Evaluation of Airborne Thermal Infrared Imagery for Locating Mine Drainage Sites in the Lower Kettle Creek and Cooks Run Basins,Pennsylvania, USA

Abstract.  High-resolution airborne thermal infrared (TIR) imagery data were collected over 90.6 km² (35 mi²) of remote and rugged terrain in the Kettle Creek and Cooks Run Basins, tributaries of the West Branch of the Susquehanna River in north-central Pennsylvania. The purpose of this investigation was to evaluate the effectiveness of TIR for identifying sources of acid mine drainage (AMD) associated with abandoned coal mines. Coal mining from the late 1800s resulted in many AMD sources from abandoned mines in the area. However, very little detailed mine information was available, particularly on the source locations of AMD sites. Potential AMD sources were extracted from airborne TIR data employing custom image processing algorithms and GIS data analysis. Based on field reconnaissance of 103 TIR anomalies, 53 sites (51%) were classified as AMD. The AMD sources had low pH (<4) and elevated concentrations of iron and aluminum. Of the 53 sites, approximately 26 sites could be correlated with sites previously documented as AMD. The other 27 mine discharges identified in the TIR data were previously undocumented. This paper presents a summary of the procedures used to process the TIR data and extract potential mine drainage sites, methods used for field reconnaissance and verification of TIR data, and a brief summary of water-quality data.     

The alteration of cell membrane of sulfate reducing bacteria in the presence of Mn(II) and Cd(II)

In this work, the effects of manganese and cadmium on the biosorption, cell membrane and growth of a sulfate reducing bacteria (SRB) strain were studied in detail. The strain of SRB used in this studied belongs to Salmonella named as Salmonella Daqing, which is isolated from Daqing oil field, China. Because of electrostatic attraction, Mn²⁺ and Cd²⁺ can be absorbed on the cell surface with negative charges. After biosorption of Mn²⁺ and Cd²⁺ on the cell surface, the morphological character of the cells changed, even some cells were almost completely deformed. The fluorescence polarization has shown a significant decrease in membrane fluidity and the increase of permeability of cell membrane. Ion analysis also revealed that permeability of cell membrane increased because of damage of cell membrane. Changes of the spectral profile of S. Daqing MF were also observed, suggesting the damages of surface groups on the cell membrane. Furthermore, low concentration of metal ions can promote growth of the bacteria, while high concentration has inhibitory effects on S. Daqing MF. The reason is attributed to the easier absorbability of nutrition due to the increased cell permeability.     

濉溪县刘楼铜铁（金）矿水文地质特征及充水因素分析

依据刘楼矿区既有地质勘查及矿山开采成果资料,对矿井水文地质特征及充水因素进行了分析,认为矿井充水水源主要是基岩岩溶裂隙水,且第四第系下部含水层天窗式补给,其水文地质条件为中等复杂。基于上述分析指出了天窗式补给部位为防治水关键部位,为该矿井及同类矿山防治水工作提供了有益参考。     

(Ti70.5Fe29.5)100-xYx合金组织和力学性能研究

对(Ti70.5Fe29.5)100-xYx(x=0,1,2,3,4)合金的组织和力学性能进行了系统的研究。结果表明：Ti-Fe-Y系三元合金组织呈现出亚共晶特征,即包括先析出枝晶状β-Ti和片层状(TiFe+β-Ti)共晶组织。其中Ti70.5Fe29.5片层状TiFe相厚度约为1μm,而(Ti70.5Fe29.5)98Y2片层状TiFe相厚度仅300 nm左右,组织得到了大幅度细化。Ti-Fe-Y系合金的强度和塑性由于组织细化程度的不同,随着Y元素含量的增加,同向呈现出先上升后下降的趋势,但较Ti70.5Fe29.5而言均得到了较大幅度的提升。对比Ti70.5Fe29.5的抗压强度2058 MPa、塑性应变量为6.0%,(Ti70.5Fe29.5)98Y2的综合力学性能最佳,其抗压强度为2447 MPa,塑性应变量为14.2%。     

铁山铁(铜)矿床地质特征及成矿作用探讨

铁山铁(铜)矿床位于长江中下游成矿带西亚带、鄂东南铁铜成矿区亚带北段.矿体主要赋存于燕山早中期侵入的闪长岩类和三叠系大冶群碳酸盐岩第三～六段的断裂复合接触带上.从岩浆的侵入到岩体结晶冷凝,接触带经历了压性到张性改造的转变.通过野外观察及室内研究,铁山铁铜矿床成矿作用主要为早期闪长岩浆熔融出富铁熔浆沿张性构造带贯入成矿,矿体与围岩呈截然接触关系,矽卡岩化较弱,后期为接触交代成矿.根据铁山铁矿床的成矿地质特征、两期成矿与先后侵入岩体在时空上的分布规律,初步建立了铁矿浆充填成矿、接触交代式成矿的成矿模式.     

煤与瓦斯突出的防治(二)

煤与瓦斯突出的防治专业知识第二个专题主要介绍了防治煤与瓦斯突出的预测、区域性防突措施及防治突出工作中常遇到三种超前距离。     

Legacy of Cyanide and ARD at a Low-Scale Gold Mine (Furtei, Italy)

A gold deposit was exploited from 1997 to 2003 at Furtei, Sardinia (Italy). Gold and silver were recovered from oxidized ores by cyanidation; copper concentrates were separated from the sulfide ores by flotation. Following unplanned closure, sulfide-rich materials derived from mining and processing residues were left on site. During operation, cyanide solutions were disposed of in a tailings impoundment. The cyanide underwent natural degradation so that by 2011, cyanide concentrations in the tailings impoundment and seeps were below the Italian limit for industrial effluents. However, during the rainy season, sulfide-rich materials in the waste rock dumps produce extreme acidic solutions and concentrations of some dissolved contaminants, especially ammonium, aluminum, arsenic, copper, iron and manganese, still exceed discharge criteria in the tailings impoundment and seeps. Highly contaminated drainage flows downstream from the mine and poses a hazard to agricultural areas.