Separation and Stabilization of Arsenic from Lead Slime by the Combination of Acid Leaching and Forming Scorodite

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1319
Author(s):  
Wenhua Li ◽  
Wei Liu ◽  
Hongwei Liu ◽  
Huanlong Wang ◽  
Wenqing Qin
Keyword(s):  
Acid Concentration ◽  
Ph Value ◽  
Arsenic Concentration ◽  
Acid Leaching ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Arsenic Content ◽  
Pressure Oxidation ◽  
Solid Ratio ◽  
Initial Ph

In this paper, a scheme is proposed for the treatment of arsenic-containing lead slime by the combination of acid pressure oxidation leaching and forming scorodite. On the basis of thermodynamic calculations, the effects of six factors including acid concentration, oxygen partial pressure (pO2), liquid to solid ratio (L/S), agitating speed, leaching time and temperature for the removal of arsenic were studied in an acid pressure oxidation leaching process, then the optimum leaching conditions were established: L/S of 10 mL/g, leaching time of 2.5 h, pO2 of 2.0 MPa, leaching temperature of 170 °C, acid concentration of 100 g/L and stirring speed of 300 r/min. Under the optimal conditions, the leaching rate of arsenic from lead slime reached 99.10% and the arsenic content of the leaching residue was about 0.80%. After a decontamination procedure, the total arsenic concentration in the acid solution obtained from leaching experiments was 37.18 g/L, and the initial pH was 0.50. Finally, as high as 98.5% of arsenic extracted from the lead slime was stabilized in the form of scorodite (FeAsO4·2H2O) by the precipitation process under the following conditions: initial pH value of 1.0, Fe(II)/As molar ratio of 1.3, pO2 of 2.5 MPa, temperature of 160 °C and precipitation time of 2.0 h.

scholarly journals Controlled Hydrothermal Precipitation of Alunite and Natroalunite in High-Aluminum Vanadium-Bearing Aqueous System

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 892
Author(s):  
Luyao Wang ◽  
Nannan Xue ◽  
Yimin Zhang ◽  
Pengcheng Hu
Keyword(s):  
Ph Value ◽  
Acid Leaching ◽  
Aqueous System ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Surface Charges ◽  
Hydrothermal Conditions ◽  
Precipitation Efficiency ◽  
Aluminum Ions ◽  
Hydrothermal Precipitation

During the acid leaching process of black shale, with the destruction of the aluminosilicate mineral structure, a large amount of aluminum (Al) is leached, accompanied by the release of vanadium (V). To separate aluminum from the vanadium-containing solution, the precipitation behavior of aluminum ions (Al3+) was investigated under hydrothermal conditions with the formation of alunite and natroalunite. In the solution environment, alunite and natroalunite are able to form stably by the Al3+ hydrolysis precipitation process at a temperature of 200 °C, a pH value of 0.4 and a reaction time of 5 h. When Al3+ was precipitated at a K/Al molar ratio of 1, the aluminum precipitation efficiency and the vanadium precipitation efficiency were 64.77% and 1.72%, respectively. However, when Al3+ was precipitated at a Na/Al molar ratio of 1, the precipitation efficiency of the aluminum decreased to 48.71% and the vanadium precipitation efficiency increased to 4.36%. The thermodynamics and kinetics results showed that alunite forms more easily than natroalunite, and the reaction rate increases with increasing temperature, and the precipitation is controlled by the chemical reaction. Vanadium loss increases as the pH value increases. It can be deduced that the ion state of tetravalent vanadium (VO2+) was transformed into the ion state of pentavalent vanadium (VO2+) in the hydrothermal environment. The VO2+ can be adsorbed on the alunite or natroalunite as a result of their negative surface charges, ultimately leading to vanadium loss.

scholarly journals Preparation of Doped Iron Phosphate by Selective Precipitation of Iron from Titanium Dioxide Waste Acid

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 789
Author(s):  
Weiguang Zhang ◽  
Ting-an Zhang ◽  
Liuliu Cai ◽  
Guozhi Lv ◽  
Xuejiao Cao
Keyword(s):  
Titanium Dioxide ◽  
Ph Value ◽  
New Technology ◽  
Aluminum Phosphate ◽  
Iron Phosphate ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Selective Precipitation ◽  
Initial Ph ◽  
Waste Acid

In view of the current situation where the acid resources and valuable components in titanium dioxide waste acid cannot be effectively extracted and are prone to secondary pollution, the research team proposed a new technology of step extraction and comprehensive utilization of titanium dioxide waste acid. In this paper, the preparation of doped iron phosphate from waste acid by selective precipitation was studied. The thermodynamics of selective precipitation, the effect of the reaction temperature, the initial pH value, the molar ratio of P/Fe, and the dispersant on the precipitation process were investigated in detail. The thermodynamics results show that iron(II) in titanium dioxide waste acid is oxidized and is preferentially precipitated with phosphoric acid to form iron(III) phosphate, when compared with other impurity ions. The experimental results show that the optimal precipitation condition is a temperature of 60 °C, an initial pH value of 2.5, an optimal P/Fe molar ratio of 1.1, and a dispersant polyethylene glycol at 5 mL (Per 50 mL of waster acid). After calcination, the precipitate mainly consists of iron phosphate and a small amount of aluminum phosphate. Meanwhile, the utilization ratios of iron and phosphorus were 98.81% and 98.39%, respectively. Moreover, the mass percentage of Fe2O3 and P2O5 and the molar ratio of Fe/P were 99.13% and 1.03, which basically met the requirements of the iron phosphate precursor.

Leaching kinetics of copper and valuable metal extraction from copper-cadmium residues of zinc hydrometallurgy by oxidation acid leaching

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jihao Guo ◽  
Hongao Xu ◽  
Bo Li ◽  
Yonggang Wei ◽  
Hua Wang
Keyword(s):  
Hydrogen Peroxide ◽  
Acid Concentration ◽  
Acid Leaching ◽  
Metal Extraction ◽  
Agitation Rate ◽  
Leaching Kinetics ◽  
Solid Ratio ◽  
Zinc Hydrometallurgy ◽  
Kinetics Of ◽  
Leaching Efficiency

Abstract Multiple purification of zinc sulfate solution is an important process for zinc hydrometallurgy, and large quantities of copper-cadmium residues are generated as byproducts in this process. Copper-cadmium residues contain a large number of valuable metals that must be recovered. A comprehensive extraction process has been proposed using sulfuric acid as the leaching reagent and hydrogen peroxide as the oxidizing reagent. The effects of acid concentration, leaching temperature, leaching time, liquid-to-solid ratio, hydrogen peroxide dosage and stirring speed on the leaching efficiency were investigated. The optimum conditions were determined as an acid concentration of 150 g/L, liquid-to-solid ratio of 4:1, hydrogen peroxide amount of 20 mL, time of 60 min, temperature of 30 °C, particle size of −d75 μm, and agitation rate of 300 r/min. It was concluded that the leaching efficiency of copper and cadmium reached 97%, but because of the existence of zinc sulfide in the residues, a lower leaching efficiency of zinc was obtained. Furthermore, the leaching kinetics of copper was also studied based on the shrinking core model. The activation energy for copper leaching was 5.06 kJ/mol, and the leaching process was controlled by the diffusion through the product layer.

Study on Leaching Zinc Calcine with High Iron

2013 ◽  
Vol 826 ◽  
pp. 118-121
Author(s):  
Jin Lin Yang ◽  
Hong Mei Zhang ◽  
Xiu Juan Su ◽  
Shao Jian Ma
Keyword(s):  
Sulfuric Acid ◽  
Acid Concentration ◽  
Great Influence ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Leaching Rate ◽  
Iron Extraction ◽  
High Iron ◽  
Solid Ratio ◽  
Leaching Efficiency

In recent years, recovering zinc from zinc calcine with high iron has been a matter of discussion. In this paper, sulfuric acid leaching was carried out to assess the effect of several parameters on zinc and iron extraction in zinc calcine with high iron in which the grade of zinc and iron is 53.90% and 19.38%, respectively. Parameters, such as stirring speed, sulfuric acid concentration, liquid to solid ratio and leaching time, were investigated. The results show that leaching time has done nothing to the leaching rate, but has great influence on leaching efficiency. Liquid to solid ratio and sulfuric acid concentration have significant influence on leaching results, and stirring rate has not obvious influence on leaching results. Under the condition of 120g/L sulfuric acid, 6:1 liquid to solid ratio, 55°C leaching temperature and 120min leaching time, the recovery of zinc and iron is 82.24% and 9.64%, respectively. It is obvious that ZnO in zinc calcine is easy to dissolve in acidity solution, which shown in two aspects: high leaching rate and high leaching speed. ZnO can be dissolved entirely in sufficient sulfuric acid in 10min.

scholarly journals Effectiveness of Fly Ash and Red Mud as Strategies for Sustainable Acid Mine Drainage Management

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 707
Author(s):  
Viktoria Keller ◽  
Srećko Stopić ◽  
Buhle Xakalashe ◽  
Yiqian Ma ◽  
Sehliselo Ndlovu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Acid Mine Drainage ◽  
Red Mud ◽  
Mine Drainage ◽  
Ph Value ◽  
Coal Fly Ash ◽  
Precipitation Process ◽  
Acid Mine ◽  
Initial Ph ◽  
Acidic Mine Water

Acid mine drainage (AMD), red mud (RM) and coal fly ash (CFA) are potential high environmental pollution problems due to their acidity, toxic metals and sulphate contents. Treatment of acidic mine water requires the generation of enough alkalinity to neutralize the excess acidity. Therefore, red mud types from Germany and Greece were chosen for the neutralization of AMD from South Africa, where this problem is notorious. Because of the high alkalinity, German red mud is the most promising precipitation agent achieving the highest pH-values. CFA is less efficient for a neutralization and precipitation process. An increase in temperature increases the adsorption kinetics. The maximum pH-value of 6.0 can be reached by the addition of 100 g German red mud at 20 °C to AMD-water with an initial pH value of 1.9. German red mud removes 99% of the aluminium as aluminium hydroxide at pH 5.0. The rare earth elements (yttrium and cerium) are adsorbed by Greek red mud with an efficiency of 50% and 80% at 60 °C in 5 min, respectively.

Atmospheric Acid Leaching of a Ferruginous Nickel Laterite

2013 ◽  
Vol 634-638 ◽  
pp. 3196-3200
Author(s):  
Kui Liu ◽  
Xue Mei Su
Keyword(s):  
Sulfuric Acid ◽  
Acid Concentration ◽  
Atmospheric Pressure ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Nickel Laterite ◽  
Nickel Extraction ◽  
Solid Ratio ◽  
Acid Consumption ◽  
Two Factors

A ferruginous nickel laterite was leached by sulfuric acid at atmospheric pressure. Nickel extraction was largely dependent on sulfuric acid concentration and leaching temperature. Besides these two factors, leaching time and liquid/solid ratio also influenced cobalt extraction significantly. Nickel was easier to be extracted than cobalt. About 95% nickel and cobalt could be extracted when leaching with 5mol/L sulfuric acid for 2h at 100°C, and the acid consumption was 1.417kg H2SO4/kg dry ore.

Removal of sulfate from wet FGD wastewater by co-precipitation with calcium hydroxide and sodium aluminate

2018 ◽  
Vol 77 (5) ◽  
pp. 1336-1345 ◽  
Author(s):  
Jicheng Yu ◽  
Jia Lu ◽  
Yong Kang
Keyword(s):  
Ph Value ◽  
Sodium Aluminate ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Operation Condition ◽  
Sulfate Removal ◽  
Aluminum Hydroxides ◽  
Initial Ph ◽  
Co Precipitation

Abstract Chemical precipitation method was adopted to remove sulfate from wet flue gas desulfurization (FGD) wastewater and mixtures of Ca(OH)2 (CH) and NaAlO2 (SA) were used as precipitants. The mechanisms of sulfate removal were explored according to the experimental and simulated results. These showed that three kinds of precipitations, which were gypsum, ettringite and co-precipitation onto aluminum hydroxides, were formed when sulfate in water reacted with CH and SA. The optimum operation condition for removing sulfate was that the molar ratio of CH/SA was 2, the initial pH value 5, the precipitant dosage 15 g/L, the reaction time 20 min, and the reaction temperature 55 °C. The sulfate was reduced from 4,881 mg/L to 784 mg/L under the optimized condition. In addition, the heavy metals and fluoride were also mostly removed. The post treatments of the supernatant illustrated that removal of sulfate from wet FGD wastewater by co-precipitation with CH and SA was a better choice.

Transformation Behavior of Molybdenum during Pressure Oxidation Process of Molybdenite Concentrate

2011 ◽  
Vol 79 ◽  
pp. 258-263
Author(s):  
Wang Zhong Mu ◽  
Ting An Zhang ◽  
Guo Zhi Lü ◽  
Zhi He Dou ◽  
Lan Hu ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Acid Concentration ◽  
Oxidation Process ◽  
Leaching Rate ◽  
Transformation Behavior ◽  
Pressure Oxidation ◽  
Molybdenite Concentrate ◽  
Solid Ratio ◽  
Sulphuric Acid Concentration ◽  
Single Factor Experiment

MoS2(AR) was used to analyze molybdenum transformation behavior in the pressure oxidation process of Chile molybdenite concentrate. Amount of NaNO3, temperature and sulphuric acid concentration were investigated on the total transform rate of Mo, leaching rate of Mo and absolute transform rate of Mo in residue. ICP, XRF, XRD were used to analyze the content and phase of elements in the molybdenite concentrate and residue. Single factor experiment results of indicate that when amount of NaNO3 is 1:4, temperature is 150°C,sulphuric acid concentration is 40g/L, oxygen partial pressure is 0.8MPa, liquid to solid ratio is 6:1(ml:g), reaction time is 120min and stirring speed is 500rpm, total transform rate of Mo is 97.95%, leaching rate of Mo is 18.48% and absolute transform rate of Mo in residue is 79.47%. Synthetical condition experiment results certified this process has the preferably reproducibility. Molybdenum could be recovered sufficiently through this method.

Research on the Extract Al2O3 from Coal Gangue

2012 ◽  
Vol 524-527 ◽  
pp. 1947-1950 ◽  
Author(s):  
Lei Zhang ◽  
Hao Wang ◽  
Yu Li
Keyword(s):  
Hydrochloric Acid ◽  
Aluminum Oxide ◽  
Acid Concentration ◽  
Acid Leaching ◽  
Coal Gangue ◽  
Hydrochloric Acid Concentration ◽  
Leaching Rate ◽  
Mass Ratio ◽  
Sample Mass ◽  
Solid Ratio

The experiments selected Wang Taipu gangue as raw materials and adopted single factor experimental method to study the leaching of aluminum oxide from gangue by using hydrochloric acid as leaching medium. The experiments studied solvent/sample mass ratio, hydrochloric acid/sample, liquid-solid ratio, hydrochloric acid concentration, leaching time and leaching temperature on Al2O3 leaching rate of coal gangue. Through the parallel experiment of the above factors, we can found that optimization conditions of hydrochloric acid leaching of alumina were: solvent /sample mass ratio: 0.20, solvent: NaF, liquid-solid ratio: 1:10, hydrochloric acid concentration: 6mol/L, leaching time: 150min, leaching temperature:110°C. In this case, the aluminum oxide of optimal leaching rate was 79.33%.

Perchlorate Removal Using the Calcination Products of Mg-Al-Fe Hydrotalcite-Like Compounds as Adsorbent

2013 ◽  
Vol 662 ◽  
pp. 520-523
Author(s):  
Ling Ling Niu ◽  
Fang He ◽  
Shang Zhen Zhao
Keyword(s):  
Ph Value ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Constant Ph ◽  
Initial Ph ◽  
Perchlorate Concentration ◽  
Perchlorate Removal ◽  
Co Precipitation ◽  
Calcined Temperature ◽  
Adsorbent Dose

The calcination products of Mg/(Al-Fe) hydrotalcite-like compounds (HMAF) were used as adsorbent to remove perchlorate in affected water. HMAF were synthesized by co-precipitation method at a constant pH value, the best calcined temperature is 500°C and the optimal Mg/Al/Fe molar ratio is 3:0.8:0.2 (CHMAF5%). Factors such as adsorbent dose, initial pH, initial perchlorate concentration affecting perchlorate adsorption were studied. Results showed that the best parameters of adsorbent dose, pH and perchlorate concentration are 0.2g, pH 4-10 and 2000µg/l, respectively. The calcination products of HMAF can be a promising adsorbent for perchlorate removal.

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