Mixed rare earth concentrate leaching with HCl-AlCl_3 solution

Abstract A method of Baotou mixed rare earth concen- trate leaching was investigated. According to the principle of complex leaching, the quadratic orthogonal regression experiment was used to investigate effect of six factors. An optimal condition of low energy and environment friendly was determined as follows： HCl acidity is 4 mol.L-1, AlCl3 concentration is 2 mol.L-l, reaction temperature is 85 ℃, reaction time is 90 rain, liquid to solid ratio is 35 ml.g-1, and stirring speed is 100 r.min-1. According to this condition, the leaching ratio of mixed rare earth con- centrate is 76.5 %. The analyses of X-ray diffraction shows that bastnasite disappears, and the main peaks of filter residue is monazite and cheralite after leaching of HCl- AlCl3 solution. The result indicates that REFCO3 of the mixed rare earth concentrate can be dissolved, but REPO4 remains in the leaching residue. This method provides a way to separate and extract rare earth.

Separation and Concentration of Indium from Leaching Solution Containing Indium, Antimony and Iron Ions

Processing conditions of effectively separating indium from the leaching solution of a smelting antimony slag were studied. For the leaching solution containing indium and antimony and iron ions, indium was separated by extracting with HDEHP kerosine solution, washing antimony and iron ions with oxalic acid solution and stripping indium with a dilute solution of hydrochloric acid. InCl 3 solution with purity above 90% is obtained. Indium can be enriched through a circulation of stripping with a dilute HCl solution. The concentration of InCl 3 solution is about 25～30 g/L.

Deep Purification of Zinc Ammoniacal Leaching Solution by Cementation with Zinc Dust

Deep purification of zinc ammoniacal leaching solution by cementation using zinc dust was studied.The effects of relative amount of metallic impurities,dosage of zinc dust,purification time,temperature,pH value and total ammonia concentration in the solution on the purification of the solution were investigated.The results indicate that total ammonia concentration in the solution had no effect on the purification,but relative amount of metallic impurities,dosage of zinc dust,purification time,temperature and pH value of the solution were the main factors influencing the purification.Keeping appropriate molar ratio of copper to cadmium or nickel to cadmium was beneficial to the cementation of cadmium.Nevertheless,the presence of cobalt went against the cementation of cadmium and cobalt.All metallic impurities could be decreased to acceptable levels under the optimized conditions of 2 g/L of zinc dust dosage,1 h of purification time,35℃,pH value 9.03 of zinc ammoniacal leaching solution.The deeply purified zinc ammoniacal solution obtained by one-stage purification meets the requirements of zinc electrowinning.

Effect of the in situ leaching solution of ion-absorbed rare earth on the mechanical behavior of basement rock

A clear understanding of the evolution characteristics of leaching solution’s damage to the basement rock of ion-adsorbed rare earth deposits is essential in the in situ leaching mining.In this study,some laboratory tests were carried out to investigate the deterioration behavior and failure mechanism of rock under the erosion of leaching solution.For this purpose,granite specimens were soaked in the leaching solution for different periods and then some physical and mechanical parameters were measured.The experimental results show that the strength of the rock without any soaking is the maximum.After 60 d,the rock strength,mass(dry)and P-wave velocity(dry)decrease to the minimum,while the porosity of the specimens reaches the maximum.Moreover,the failure pattern of the specimens in the uniaxial compression tests is affected as the soaking time increases.The scanning electron microscopy(SEM)image results indicate that the erosion of quartz crystals inside the rock specimens gets more intense with the increase of soaking time.Also,the internal crystal failure mode gradually changes from the trans-granular to the inter-granular.The insights gained from this study are helpful for better understanding the evolution characteristics of leaching solution’s damage to the basement rock of ionadsorbed rare earth deposits.

Leaching kinetics of low-grade copper ore with high-alkality gangues in ammonia-ammonium sulphate solution

The leaching kinetics of low-grade copper ore with high-alkality gangues was studied in ammonia-ammonium sulphate solution.The main parameters,such as ammonia and ammonium sulphate concentrations,particle size,solid-to-liquid ratio and reaction temperature,were chosen in the experiments.The results show that the increase of temperature,concentrations of ammonia and ammonium sulphate is propitious to the leaching rate of copper ore.The leaching rate increases with the decrease of particle size and solid-to-liquid ratio.The leaching rate is controlled by the diffusion through the ash layer and the activation energy is determined to be 25.54 kJ/mol.A semi-empirical equation was proposed to describe the leaching kinetics.

Leaching of Silver from Boorchi Ag-Pb Ore in Mongolia with Acidic Thiourea Solution

A hydrometallurgical process to extract silver from the silver-lead ore in Boorchi,Mongolia by using thiourea leaching solution is studied in this work.Through the observation of optical and scanning electron microscopes,and energy spectral analysis,it is determined that 5 kinds of silver minerals exist in the ore,including argentite,Ag-tetrahedrite,Ag-Zn-Sb-tetrahedrite,freibergite and acanthite.The experimental results of direct thiourea leaching of the ore show that 56%～60% of silver is leached.The main reason for the low leaching rate is due to silver minerals enveloped in galena and other minerals,even though the ore is ground to the particle size of 75μm.When the ore is pretreated with ammonium carbonate solution under oxidation,the experimental results of thiourea leaching show that the leaching rate of silver increases to near 75% with the pretreatment.Based on the leaching experiments,a principle hydrometallurgical technological route to extract silver from the Ag-Pb ore is proposed.

Leaching Gold Using Oxidation Products of Elemental Sulfur in Ca(OH)_2 Solution under Oxygen Pressure

A gold leaching process by using in situ oxidation products of added elemental sulfur in Ca(OH)2 solution was investigated. A gold concentrate containing 45 g/t Au was tested and 85%~87% of gold were leached. The leached gold depends mainly on the initial molar ratio of elemental sulfur to the hydroxyl ion, the consumption of oxygen and the reaction temperature. Adding some surfactants, such as lignosulfonic calcium, at lower concentration increased the leached Au but at higher concentration decreased it. Both of thermodynamic analysis and experimental results show that thiosulfate is the major complexing agent for gold in the process.

Gold leaching with elemental sulfur in alkaline solutions under oxygen pressure

A gold leaching process by using oxidation products of elemental sulfur in alkaline solutions was proposed and investigated. A gold concentrate and a residue from an arsenic refractory gold concentrate by acidic oxidation leaching were tested. The residue contains 16.3% elemental sulfur and no more elemental sulfur was added in tests. For the concentrate elemental sulfur was added before leaching tests. The leaching ratio of gold depends mainly on the initial equivalent ratio of elemental sulfur to hydroxyl ions, the consumption of oxygen and the reaction temperature in the process. Analysis of the experimental results shows that thiosulfate is the majority complexing reagent for gold in the process. Over 90% gold was leached from the residue and 82%87% from the concentrate by using this process.

EXTRACTION MECHANISM OF CERIUM(Ⅳ) AND FLUORINE(I)IN THE SEPARATION PROCESS OF BASTNASITE LEACH SOLUTION BY CUNEX 923

The extraction equilibrium of cerium(IV) and fluorine (I) from H2SO4 solution by Cyanex 923 is studied. The extraction mechanism of Ce(IV) and F(I) by Cyanex 923 is determined by the method of slope analysis. The results show that Cyanex 923 can extract HF as HF&middotL and Ce4+ together with HF as Ce(HF)(HSO4)2(SO4)&middot2L by which HF comes into the organic phase mainly when there is Ce4+ in the solution, where L is the extractant. Temperature does not affect the extraction. The IR spectra of purified Cyanex 923 saturated with Ce(IV) and HF are discussed.

Mathematical model for coupled reactive flow and solute transport during heap bioleaching of copper sulfide

Based on the momentum and mass conservation equations,a comprehensive model of heap bioleaching process is developed to investigate the interaction between chemical reactions,solution flow,gas flow,and solute transport within the leaching system.The governing equations are solved numerically using the COMSOL Multiphysics software for the coupled reactive flow and solute transport at micro-scale,meso-scale and macro-scale levels.At or near the surface of ore particle,the acid concentration is relatively higher than that in the central area,while the concentration gradient decreases after 72 d of leaching.The flow simulation between ore particles by combining X-ray CT technology shows that the highest velocity in narrow pore reaches 0.375 m/s.The air velocity within the dump shows that the velocity near the top and side surface is relatively high,which leads to the high oxygen concentration in that area.The coupled heat transfer and liquid flow process shows that the solution can act as an effective remover from the heap,dropping the highest temperature from 60 to 38 °C.The reagent transfer coupled with solution flow is also analyzed.The results obtained allow us to obtain a better understanding of the fundamental physical phenomenon of the bioleaching process.

Dynamic experiment and numerical simulation of solute transmission in heap leaching processing

Solute transmission in saturated ore heap was studied numerically and experimentally. The convection-diffusion equation (CDE) used to describe the mass transportation in porous media was solved by characteristic difference method to give the distribution of the concentration of ferrous ion in the ore column. To calibrate the computational model, a column test was performed using infiltration of sulfide ferrous solution (the initial concentration is c0=0.04 mol/L) on a 100 cm high column composed of ore particles smaller than 10 mm for 2.5 h. The numerical analysis shows that the results obtained from numerical modeling under the same operating conditions as used for column test are in good agreement with those from experimental procedure on the whole trend, which indicates that the model, the numerical method, and the parameters chosen can reflect the rule of ferrous ion transmission in ore heap.

Experimental Study of Preferential Solute Transportation During Dump Leaching

The production of dump leaching of the Dexing Copper Mine was affected by a preferential solution flow. Formative mechanism of the preferential solution flow was investigated by analyzing the relationship between both dump permeability and surface tension and ore diameter. The preferential solution flow occured in the fine ore area when the application rate was low. The preferential solution flow entered into the coarse ore area because the negative pore water pressure disappeared with an increase of the application rate. The preferential solute transportation experi- ment was conducted by selecting NaCl as mineral. Results of the experiment showed that the concentration of the out- flow solution reduced over time. The concentration of the coarse ore area outflow solution was greater than that of the fine ore area. The process of NaCl leaching can be divided into two stages. NaCl was carried out directly by diffusion- convection during the first stage, so the leaching rate increased sharply. But in the second stage, only a small amount of NaCl dissolved in the immobile water. The leaching rate increased slowly because NaCl, dissolved in the immobile wa- ter, can only be leached by diffusion.

Extraction of copper from bacterial leach solution using LIX98

Extraction of copper from bacterial leach solution using Lix984 had been performed. It was found that the main factors influencing extraction yield of copper are the phase ratio and the concentration of extractant, following the pH of solution and extraction time and the order of factors influencing the separation rate is the pH of solution, the concentration of extractant, the extraction time and the phase ratio. The best conditions obtained by the orthogonal tests are as follows: the extractant concentration 4%, extraction time 3 min, phase ratio 1∶1, pH of solution 2.

Leaching vanadium by high concentration sulfuric acid from stone coal

An effectively new technology of extracting vanadium from stone coals by high concentration sulfuric acid was researched. The effect of the concentration of sulfuric acid,leaching temperature,leaching time and helper leaching agent on the extraction of vanadium was explored.The results show that the optimal conditions of extraction are as follows:the concentration of sulfuric acid is 6 mol/L,the ratio of liquid to solid is 3-1;the temperature is 90℃;the leaching time is 3-5 h,the diameter of the ore particle is less than 180μm,and the concentration of helper leaching agent R is 6%.Under these conditions,the extraction of vanadium can reach 95.86%.

Simulation of coupled flowing-reaction-deformation with mass transfer in heap leaching processes

Governing equations for a fully coupled flowing-reaction-deformation behavior with mass transfer in heap leaching are developed. The model equations are solved using an explicit finite difference method under the conditions of invariable application rate and constant hydraulic head. The distribution of the degree of the saturation, as well as the distributions of the concentration of the reagent and the solute is given. A cubic relationship between the mineral recovery and the leaching duration is obtained based on the numerical results. The relationship can be used to predict the recovery percentage of the valuable metal.

Agglomeration and leaching behaviors of copper oxides with different chemical binders

The chemical binder is one of the critical factors affecting ore agglomeration behavior and leaching efficiency.In this study,we in-vestigated the effect of the type of binder and mass fraction of the H_(2)SO_(4)solution used on the curing,soaking,and leaching behavior of ag-glomerations.The results revealed that Portland cement(3CaO·SiO_(2),2CaO·SiO_(2),and 3CaO·Al_(2)O_(3))was the optimal binder for obtaining a well-shaped,stable agglomeration structure.A higher extraction rate was achieved when using Portland cement than that obtained using sodi-um silicate,gypsum,or acid-proof cement.An excessive geometric mean size is not conducive to obtaining well-shaped agglomerations and desirable porosity.Using computed tomography(CT)and MATLAB,the porosity of two-dimensional CT images in sample concentrations L1-L3 was observed to increase at least 4.5vol%after acid leaching.Ore agglomerations began to be heavily destroyed and even to disinteg-rate when the sulfuric acid solution concentration was higher than 30 g/L,which was caused by the excessive accumulation of reaction products and residuals.

Bioleaching of low-grade copper sulphides

The bioleaching behavior of low-grade copper sulphides under the condition of preferential solution flow was investigated through experiments. The experiment of bioleaching was conducted within the multifunction autocontrol bioleaching apparatus. The results show that the concentrations of Cu2+ and total Fe increase slowly at the beginning. The recovery rate decreases with the increase of depth of dump. The preferential solution happens within the fine region when the application rate is low, and the recovery rate of the fine region is higher than that of the coarse region. The content of fine ore particles within both fine and coarse regions increases during the leaching period, and the preferential solution flow shifts from fine region to coarse region. The surface of the ores at the top of dump is attacked seriously, and the ores in the middle is attacked slightly. There are plenty of crackles on the surface of bottom ores because of the precipitation layer on the surface.

Alkaline extraction characteristics of steelmaking slag batch in NH_4Cl solution under environmental pressure

In order to obtain better carbonation effect,extraction behavior of slag batch is necessary to study.Relevant parameters like selective extraction yield were originally discussed.The relationship between selective extraction yield and conversion ratio was systemically focused on.The results show that alkaline earth metal conversion ratio is changed with leaching time and NH4Cl concentration by first order exponential,and the maximum conversion for calcium keeps about 68% at 120 min in 0.4 mol/L NH4Cl solution,while leaching temperature and particle size have a linear effect on conversion ratio.Selective extraction yield of calcium is more than 93%,and the value of Mg is less than 5%.Apparent layer bands of silicon and calcium appear in the surface area through morphology detection of slag after leaching,and the case for 38-75 μm slag batch is more obvious than 75-150 μm slag and slag with larger particle size when leaching in 0.4 mol/L NH4Cl solution for 90 min at 60 ℃.

铁尾矿酸浸液制备聚氯化铁的试验研究

为探索某选矿厂铁尾矿回收利用的新途径,对铁尾矿酸浸液制备聚氯化铁的试验过程进行了研究,并将自制的聚氯化铁应用到高岭土悬浊液的混凝试验中测试产品的絮凝性能。结果表明:聚合的适宜条件为温度为40℃、pH为1.0、聚合时间为3h,在该条件下合成的聚氯化铁盐基度为20.91%,符合相关标准,影响聚合过程因素的主次顺序依次为聚合温度、pH、聚合时间;混凝的适宜条件为聚氯化铁投加量为250 mg/L、pH为7.0、搅拌时间为3min、温度为20℃、混凝时间为60min,在该条件下浊度去除率为95.54%,产品除浊效果良好。