从氨性溶液中萃取分离铜、钴的研究

研究了不同萃取剂从氨性溶液中分离铜、钴的过程。采用LIX984N作萃取剂,经一级萃取,溶液中铜的萃取率大于99%;用180g/L硫酸溶液对负载有机相进行反萃,经二级逆流反萃,铜的反萃率达99%以上。采用LIX54-100作萃取剂,经过四级逆流萃取铜的萃取率达到99 53%;用30g/L硫酸溶液对负载有机相进行反萃,经一级反萃,铜的反萃率大于99 9%。在上述萃取过程中,钴均不被萃取。     

Evaluation of Hydrotalcites Produced in Seawater for Remediation of Metalliferous Acid Mine Drainage and Submarine Placement

Uncontrolled release of acid mine drainage (AMD) causes widespread detrimental impacts on the receiving environment. Thus, effective treatment to neutralise AMD effluent pH and capture a suite of metals is required. In-situ hydrotalcite (HTC) precipitation is an emerging technology for AMD remediation. HTC has an inherent capacity to accommodate a range of cations and anions during in situ formation, offering a method of broad-spectrum contaminant removal. This study explored the feasibility of using seawater as an Mg source and synthetic AMD in HTC formation. The HTC was formed from a stoichiometric combination of synthetic AMD and seawater. While three initial stoichiometric M²⁺:M³⁺ ratios of 2:1, 3:1, and 4:1 were investigated, only HTC with an M²⁺:M³⁺ ratio of 2:1 was generated, as confirmed by both mineralogical and geochemical analyses. Importantly, the HTC was demonstrated to effectively remove a suite of metals present in AMD such as Cu, Zn, Al, and Mn with removal rates of between 99.97 to 99.99%. The HTC precipitate contained ≈6.6% Cu and 4.1% Zn, and thus shows the potential, if required, for future metal recovery. Since submarine placement is often used in metal mining and processing operations proximal to the coast, the stability of the HTC precipitate in seawater was also investigated. Importantly, only 0.2% of the Cu and 1.1% of the Zn within the HTC were subsequently leaching in decreasing increments into seawater over 30 days with decreasing increments after the initial seven days. This indicates robust element retention and confirms the potential of HTC for AMD remediation with direct submarine placement.

     

The Hydrogeochemistry of Arsenic in the Clara Mine,Germany

Abstract.   The oxidative dissolution of primary arsenic-bearing sulfide minerals in barite-fluorite veins is a potential source of arsenic in the Clara Mine. Geological structures, especially the mineral veins, provide potential pathways for the water. The highest arsenic concentrations are found in ground water within the eastern part of the mine. Arsenic and major ions are positively correlated and provide evidence that arsenic is likely derived locally from the water-vein/water-rock interaction. Geochemical modeling with PHREEQC shows all the arsenate mineral phases to be significantly undersaturated, although secondary arsenate minerals are common in the oxidized part of the deposit. The mine waters plot near the boundary of Fe(OH)₃ and Fe²⁺ in the pH-Eh diagram for the As-Fe-S-H₂O-system. Arsenic occurs as the 5-valent species and . Statistical analysis illustrates a strong association between As, Fe, pH, and HCO₃. Oxidation of the primary As-bearing minerals, such as pyrite and arsenopyrite, and the subsequent behavior of the oxyanion, arsenate, generally controls the distribution and speciation of arsenic. The low concentrations of dissolved As is due to co-precipitation and adsorption of arsenate by Fe, Al, and Mn (oxy)hydroxides.     

Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping

Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping was carried out. The influence of equilibration time, equilibrium pH and extractant concentration on the extraction of both the metals was studied. It was found that the copper extraction equilibrium was reached in a shorter time than the nickel extraction equilibrium. Nickel extraction decreases above an equilibrium pH of 9.0, while the extraction of copper remains unaffected by the changes in the equilibrium pH range of 7–10. Co-extraction, ammonia scrubbing and the selective stripping of copper and nickel were performed for a solution containing 3 g/l each of copper and nickel and 60 g/l ammonium carbonate. The extraction and the percentage stripping of copper and nickel were almost quantitative.     

Extraction of copper, nickel and cobalt from the leach liquor of manganese-bearing sea nodules using LIX 984N and ACORGA M5640

This paper describes a method, using sulfuric acid and activated charcoal for leaching Polymetallic sea nodules. Resulting leach solutions were examined for the extraction of copper, nickel and cobalt using LIX 984N and ACORGA M5640 in kerosene. After the removal of manganese and iron impurities from the leach liquor, copper and nickel were co-extracted leaving cobalt in the raffinate. The selective stripping of nickel and copper produces solutions rich in these metals, while regenerating the solvent for reuse.     

Extractive separation of copper and nickel from copper bleed stream by solvent extraction route

Bleed stream from electro refining step of copper smelter was processed to recover the metals as high value products such as copper and nickel powders or salts. The process consists of partial decopperisation of the bleed stream followed by crystallization of a mixed salt of copper and nickel sulphate, leaching of the mixed salt, removal of iron, solvent extraction for the separation of copper and nickel and winning the solution to produce metal powders. After partial decopperisation of copper bleed stream, the resultant solution was subjected to crystallization which produces composite crystals with the chemical composition of 8.4–12.5% Cu, 13.7–14.38% Ni and 1–2 ppm of Fe as impurity. This mixed salt was leached with water and was treated for iron precipitation. The purified solution was subjected to solvent extraction using two solvents namely LIX 84 or Cyanex 272. A 20% LIX 84 in kerosene extracted 99.9% copper and 0.059% nickel at a pH of 2.5, similarly a 5% Cyanex 272 in kerosene extracted 98.06% copper and 0.51% nickel at a pH of 4.85. LIX 84 was used for metal separation in the mixer-settler unit and a flow sheet was developed using this solvent. The pure solutions of copper after stripping it from the loaded organic and nickel left in the raffinate were further electrolysed to produce pure copper (99.9%) and nickel (99.8%) powders, alternatively pure sulphate salts could also be crystallized. Since it is well known that Cyanex 272 is used for the separation of cobalt and nickel, a few experiments were performed on the extraction of copper by using Cyanex 272. A complete study is yet to be done to develop a flow sheet by using this solvent.     

Production of high purity molybdenum compounds from a Cu–Mo acid-washed liquor using solvent extraction. Part 1: Laboratory studies

Solvent extraction, using Alamine 304-1 for loading (extraction) and ammonia for stripping, was used for selectively recovering molybdenum from acid wash liquor produced by a Mo processing plant. The results showed that the extraction could be completed in 3 stages, using Alamine 304-1 as the extractant (10%, v/v in Anysol 150 diluent), with almost all the Mo(VI) recovered from an acidic sulfate wash liquor, containing 10–15 g/L Mo(VI), 10 g/L Cu(II) and 2 g/L Fe(III), using an O/A volumetric ratio of 3:2. Using ammonia (12.5%, w/v), at an O/A ratio of 5:1, all the Mo(VI) from an Alamine liquor containing 17.5 g/L Mo could be removed in one strip, yielding a solution with 87.0 g/L Mo(VI). High purity (>99.9%) MoO₃ and CaMoO₄ were produced from this pure liquor via an intermediate hydrate precipitate (MoO₃ · H₂O). The study also showed that understanding the stability and speciation of various soluble and solid Mo species are essential for the development of an efficient recovery process.     

A novel low pH sulfidogenic bioreactor using activated sludge as carbon source to treat acid mine drainage (AMD) and recovery metal sulfides: Pilot scale study

In this work a pilot scale sulfidogenic bioreactor was used to treat acid mine drainage (AMD) from Zijinshang copper mine. In this process, S²⁻ produced in the Up-flow Anaerobic Sludge Bed (UASB) reactor were recycled in the two precipitation tanks for copper and iron precipitation, activated sludge from local waste water treatment plant was used as the carbon source. The reactor were steady operated in acid condition (with no pH control) for 4 month, AMD with a copper concentration of 100–120 mg/L, iron concentration of 170–200 mg/L, sulfate concentration of 2000–2500 mg/L and pH of 2.34–2.56, were feeding into the reactor under a feed rate of 1 m³/days and HRT of 3 days, copper and iron removal were 60.95%, 97.83% respectively. The precipitant in the precipitation tank containing 15.7% Cu and 22.66% Fe, thus indicating a recovery possibility of copper by pyrometallurgy process. From these results we can conclude that an SRB process would be a viable method of treating Zijinshan AMD.     

Lime Treatment of Mine Drainage at the Sarcheshmeh Porphyry Copper Mine,Iran

Laboratory and field treatment tests were performed to evaluate the effectiveness of lime treatment for mitigation of environmental effects of acid mine drainage (AMD) at the Sarcheshmeh porphyry copper mine. AMD associated with the rock waste dumps is contaminated with Al (>36,215 μg/L), Cd (>105 μg/L), Co (>522 μg/L), Cu (>53,250 μg/L), Mn (>42,365 μg/L), Ni (>629 μg/L), and Zn (>12,470 μg/L). The concentrations of other metals (Fe, Mo, Pb, and Se) are low or below detection limits (As, Cr, and Sb). Due to the very high Al and Mn content and the low concentration of Fe, a two-stage lime treatment method was chosen for the laboratory tests. In the first stage, the AMD was treated at four pH set points: 7.5, 8.9, 9, and 10. In the second stage, after removing the sludge at pH 9, treatment was continued at pH 10 and 11. The results indicated that a two-stage treatment method was not necessary because elements such as Al, Cu, Co, and Zn were easily treated at pH 7.5, while complete removal of Cd, Mn, and Ni only required a pH of 10. Increasing pH during the treatment process only caused a slight increase in Al. Field treatment tests support the laboratory results. Lime treatment of highly contaminated AMD from dump 11, using simple low density sludge pilot scale equipment, show that contaminant metals are treatable using this method. The mean treatment efficiency for contaminant metals was 99.4% for Al, % for Cd, 99.6% for Co, 99.7% for Cu, 98.5% for Mn, 99.7% for Ni, 99% for U, and 99.5% for Zn. The optimum pH for AMD treatment by lime was in the range of 9–10. The produced sludge in the treatment process was highly enriched in the contaminant metals, especially Cu (>7.34%), Al (>4.76%), Mn (>2.94%), and Zn (>1.25%). A correlation coefficient matrix indicates that the distribution pattern of the contaminant metals between soluble and precipitated phases is consistent with the hydrochemical behavior of the metals during the lime treatment process.     

Enhancement of Sludge Sedimentation Properties in a Concentrated Acid Mine Drainage Using Nano- and Micro-magnetite Particles

Conventional treatment of AMD involves neutralization with consequent precipitation of metals as hydroxides. In AMD with a high concentration of metals, the settling rate of the sludge/water interface is low. We investigated the use of nano- and micro-magnetite particles to assist the settling and thickening of floc particles. The magnetite was produced from ferrous sulphate crystals (melanterite, Fe₂SO₄·7H₂O) obtained by leaching pyrite from a coal mine. AMD was obtained from the treatment plant at the same mine and the water was neutralized with Ca(OH)₂ at pH 8.7?±?0.1. Laboratory studies were conducted in 1 L test tubes with and without the addition of magnetite particles and a flocculant. Sedimentation curves (interface settling) were generated to evaluate the rate of sedimentation. For the studied effluent, the best option was 4 g L^?1 of magnetite particles and 5 mg L^?1 of high molecular weight anionic polyacrylamide. The magnetite particles were recovered magnetically from the sludge with ≈ 90% efficiency. Thus, the combined use of magnetite and a flocculant increased the sludge settling rate and, consequently, reduced the area needed for settling basins.

     

Development of a process for the separation of zinc and copper from sulfuric liquor obtained from the leaching of an industrial residue by solvent extraction

This paper describes a study of the separation of zinc and copper from the leach liquor generated in the treatment of the zinc residue (29.6 g/L Zn and 37.4 g/L Cu) by liquid–liquid extraction. In it, the influence of the extractant type and concentration, aqueous phase acidity, contact time and stripping agent concentration were investigated. Organophosphorus extractants (D2EHPA, IONQUEST®801 and CYANEX®272) and the chelating extractants (LIX®63, LIX®984N and LIX®612N-LV) were also investigated. The organophosphorus reagents are selective for zinc, while the chelating extractants are selective for copper. In the experiment, D2EHPA was found to be the best extractant. A sulfuric acid solution was used in the stripping study. Five continuous experiments were carried out until an optimal condition for the separation of the metals Zn and Cu was achieved. Experiment 5 was carried out in three extraction steps, three scrubbing stages and five stripping stages. In this experiment, a pregnant strip solution containing 125 g/L Zn and 0.01 g/L Cu was obtained and the concentration of the metals in the raffinate was 28.3 g/L Cu and 0.49 g/L Zn.     

Preparation of layered nickel aluminium double hydroxide from waste solution of nickel

The separation of nickel has been carried out from a waste solution containing 3.18 g/L Ni with other impurities such as Fe, Zn, Cu and As. Iron was removed by precipitation and Cu and Zn were removed by solvent extraction using LIX 622N and NaTOPS-99, respectively. After removal of all these impurities nickel was extracted by 1.5 M NaTOPS-99 in two counter-current stages at A:O ratio of 3:1 and the loaded organic was stripped with 30 g/L H₂SO₄ at phase ratio of unity. The strip solution of nickel was treated with Al₂(NO)₃ · 9H₂O for co-precipitation by increasing the pH of solution with 1 M NaOH up to 10. The Ni–Al layered double hydroxide was confirmed through XRD characterization.     

Preparation of immobilized sulfate reducing bacteria (SRB) granules for effective bioremediation of acid mine drainage and bacterial community analysis

Heavy metal-resistant immobilized sulfate-reducing bacteria (SRB) granules were prepared to treat acid mine drainage (AMD) containing high concentrations of multiple heavy metal ions using an up-flow anaerobic packed-bed bioreactor. The bioreactor demonstrated satisfactory performance at influent pH 2.8 and high concentrations of metals (Fe 463 mg/L, Mn 79 mg/L, Cu 76 mg/L, Cd 58 mg/L and Zn 118 mg/L). The effluent pH ranged from 7.8 to 8.3 and the removal efficiencies of Fe, Cu, Zn and Cd were over 99.9% except for Mn (42.1–99.3%). The bacterial community in the bioreactor was diverse and included fermentative bacteria and SRB (Desulfovibrio desulfiricans) involved in sulfate reduction. The co-existing anaerobic fermentative bacteria (Clostridia bacterium, etc.) with the ability to use lactate as electron donor could explain the differences between actual lactate consumption and what would be expected based solely on sulfate reduction.     

Biotreatment of As-containing simulated acid mine drainage using laboratory scale sulfate reducing upflow anaerobic sludge blanket reactor

Heavy metal contamination of water sources can occur from the discharge of acid mine drainage (AMD). This study assessed sulfidogenic treatment of As-, Fe-, Zn-, Ni- and Cu-containing AMD in an upflow anaerobic sludge blanket (UASB) reactor, operated for approximately 500 days. Sulfate reducing granules were successfully enriched with synthetic wastewater and sulfate concentration decreased from 2000 mg/L in the influent to 100–200 mg/L in the effluent. The pH increased from 3–4 to 6–8 as a result of biogenic alkalinity production. Arsenic removal was not detected in the absence of heavy metals, possibly due to the high dissolved sulfide concentration. In the presence of heavy metals, and at low dissolved sulfide concentrations, As removal efficiency increased to 98–100% likely due to the formation of arsenopyrite (FeAsS) or the adsorption of As on metal sulfide precipitates. Fe, Cu, Ni and Zn removal efficiencies approached 99% in the presence of dissolved sulfide. When hydrogen sulfide generation was insufficient to precipitate all of the metals, Fe was detected in the UASB effluent. The results showed that As-, Fe-, Zn-, Ni- and Cu-containing AMD can be effectively treated by sulfate reducing granules in UASB reactors.     

某难选富氧化铜矿溶剂萃取工艺研究

国外某难选氧化铜矿平均含铜6.91%,采用机械搅拌硫酸浸出,浸出溶液含铜高达～30.0g/L。针对该高浓度硫酸铜溶液,进行了M5640 煤油萃取提铜的工艺试验研究,结果表明,以M5640为萃取剂、铜电积废液为反萃剂,在合适的相比条件下,经5级萃取、2级反萃,获得符合铜电积工艺要求的纯净硫酸铜溶液。     

Treatment of Mine Water by a Microbial Mat: Bench-scale Experiments

Abstract.   We investigated the treatment of acid mine drainage (AMD) by a blue-green algae-microbial consortium and substrate (containing powdered goat manure, wood chips, and soil) in 1 m³ bench scale biological treatment test cells. The microbial mat resulted from the interaction of bacteria and filamentous blue-green algae (predominantly Oscillatoria spp). The experiments were carried out for different water column heights, and were evaluated for 24, 48, 72, 96, and 168 hours of retention. Within 24 hours of retention, the pH increased from 2.93 to 6.78 as net alkalinity went from -125 mg/L to 197 mg/L as CaCO₃. Turbidity decreased by 33–54%, sulphate decreased by 23–29%, and hardness decreased by 19 to 26%. We also observed that: 95% of the Fe, 79–97% of the Cu, 84–86% of the Zn, 88% of the Pb, 59–83% of the Co, 22–62% of the Ni, and 28–45% of the Mn were removed. A blue-green algae/microbial mat consortium may be a cost–effective treatment technique for removing metals from AMD.     

A Bench-scale Assessment of a Combined Passive System to Reduce Concentrations of Metals and Sulphate in Acid Mine Drainage

Abstract  Passive treatment of acid mine drainage (AMD) requires a combined strategy to minimize the effect of climatic variability on the treatment performance of the system. A vertical-flow combined passive treatment system was developed and evaluated in a bench-scale laboratory test for a 290-day period. The combined system consisted of four components with specific treatment functions: an oxidation/precipitation basin for excess iron removal; a peat biofilter for heavy metal sorption and the establishment of anoxic conditions; a bioreactor for alkalinity generation and sulphate reduction; and an anoxic limestone drain for alkalinity addition. The benchscale system was dosed with moderate strength synthetic AMD at a surface loading of 95 L/m²/d, and operated under continuous flow conditions. Removal efficiencies were 99.7%, 99.9%, 99.9%, 98.6%, 98.2%, and 99.9% for Fe, Al, Zn, Mn, Ni, and Cu, respectively, while Cd remained more mobile with a removal efficiency of 66.5%. Sulphate concentrations were reduced from 3030 mg/L to 814.9 mg/L and the acidic drainage was neutralized to an effluent pH of 7.2 and an alkalinity of 1353.6 mg/L (as CaCO₃).     

Use of landfill leachate as a carbon source in a sulfidogenic fluidized-bed reactor for the treatment of synthetic acid mine drainage

High rate sulfate reducing bioreactors can be effectively used in the treatment of acid mine drainage (AMD). The main disadvantage of sulfate reducing bioreactors is the requirement of a suitable carbon source and electron donor as the dissolved organic carbon content of AMD is usually quite low. In this study, a landfill leachate was used as a low-cost carbon source for sulfate reducing bacteria in a fluidized-bed (FBR) reactor for the treatment of synthetic AMD. Ethanol was replaced with leachate in the feed of FBR operated longer than 150 days at 35 °C. Although sulfate reduction rates decreased appreciably when ethanol (3.44 g sulfate/L/d) was replaced with leachate (0.90 g sulfate/L/d), leachate-fed FBR still performed well as the pH increased to neutral values, soluble metal removals were 82–99.9%, and total metal removals were 80–99.9%. In the case of leachate, electron flow to sulfate reduction decreased significantly. Higher performance may be achieved at chemical oxygen demand (COD)/sulfate ratios higher than 1.0. This study showed that leachate may be used as a low-cost soluble substrate for sulfate reducing bacteria in high rate bioreactors for AMD treatment.     

The application of wood ash as a reagent in acid mine drainage treatment

The paper deals with a possible utilisation of wood ash as a reagent in treating acid mine drainage (AMD) from opencast mining of brown coal. Wood ash samples were obtained having combusted deciduous and coniferous tree wood in a household furnace. The dominant mineral phases in wood ash are calcite, quartz, lime and periclase. The used AMD is characteristic of high contents of sulphates, iron, manganese, heavy metals and low pH. The AMD treatment process included dosing of wood ash to adjust pH values about 8.3 (a dose of 0.5 g l⁻¹) or calcium hydroxide (a dose of 0.2 g l⁻¹) for comparison. The reaction time was 20 min. Dosing of wood ash in AMD resulted in an increase of pH in solution from 3.5 to 8.3, which caused the removal of metal ions mainly by precipitation, co-precipitation and adsorption. Comparing the application of Ca(OH)₂ in AMD treatment, at an almost identical pH value the concentrations fell in both cases for Fe, Mn, As, Co, Cu, Ni, Zn, Mg, Al and Mo. Applying wood ash the drop was even more distinct in Mn, Zn and Mg. The results of sedimentation tests in an Imhoff cone confirm that the settling capacities of sludge using wood ash are significantly better than when using calcium hydroxide in acid mine drainage treatment.     

从铅冰铜浸出液中萃取分离铜

介绍了以铅冰铜特定工艺条件下的氧压浸出液为原料,用ZJ988溶剂萃取分离回收铜的试验研究。考察了不同有机相浓度、相比、混合时间的萃取和反萃效果,并进行了若干多级逆流试验。最终得出采用有机相浓度40%,相比O/A=3/1,五级逆流萃取方式可提取出原液中98.13%的铜。