Jian Jun Fang

Reaction kinetics of malachite in ammonium carbamate solution

The dissolution of malachite particles in ammonium carbamate (AC) solutions was investigated in a batch reactor, using the parameters of temperature, AC concentration, particle size, and stirring speed. The shrinking core model was evaluated for the dissolution rate increased by decreasing particle size and increasing the temperature and AC concentration. No important effect was observed for variations in stirring speed. Dissolution curves were evaluated in order to test shrinking core models for fluid-solid systems. The dissolution rate was determined as being controlled by surface chemical reaction. The activation energy of the leaching process was determined as 46.04 kJ mol−1.

Recovering copper from volcanic ASH by NH3 · H2O–NH2COONH4

Volcanic ash from Xinjiang in the PRC contains malachite and cuprite. The volcanic ash has a copper content of 1.29%. However, because of severe argillization it is difficult to recover the copper through enrichment by flotation. Because the ash contains significant amounts of calcium and magnesium carbonates leaching the ash with acid requires a large amount of acid. We thus studied the use of ammonia-water and ammonium carbamate as effective leaching agents for copper. Leaching with ammonia-water and ammonium carbamate does not affect gangue minerals such as quartz and calcite and it can also promote the dissolution of minerals that contain copper. This leaching agent is highly specific. Using this system we recovered more than 90% of the copper from the volcanic ash. Higher reaction temperatures, smaller ore particle sizes, a higher stirring speed, a higher liquid to solid ratio and an increase in the agent’s concentration increased the copper leaching rate. SEM analysis, the activation energy (7.827 kJ/mol) and kinetics data comprehensively indicate that the reaction of copper minerals in the ammonia-water and ammonium carbamate system is controlled by internal diffusion.

Application of Intensifying Secondary Concentration Technology in Reverse Flotation of Bauxite

In order to resolve the problem of fine particle flotation in the reverse flotation of bauxite. a new method of intensifying secondary concentration technology was firstly advanced, and author applied it to ore, achieved eximious experimentation index. The reverse flotation tests of intensifying secondary concentration aiming at bauxite from Guizhou province were studied. The results show that diaspore concentrate directly used in the Bayer-mineral processing method can be obtained by using the intensifying secondary concentration technology without pre—desliming. The average A/S of the concentrate is 10.28 with a recovery rate of 85.41%.

Effect of supercritical CO 2 on various rank coals: implications for CO 2 sequestration in coal seams with enhanced coalbed methane recovery

Sequestration of CO2 in coal seams with enhanced coalbed methane recovery (CO2-ECBM) can mitigate CO2 emissions. In this work, the effects of the supercritical CO2 fluid on the physicochemical property of coals were elucidated. The results show that CO2 interaction can mobilise the volatile hydrocarbons in the coal matrix and subsequently result in the decrease of volatile matter content. The volatile matter contents of coals decrease with temperature, pressure and injection rate of CO2 interaction. The extracted volatile matters are of biological toxicity, thus CO2-ECBM process should be operated at the optimum temperature, pressure and CO2 injection rate. The moisture contents of Zhangji coal and Liulin coal after CO2 interaction increase which implies that the pore morphology of the above two coals grows up. For low rank Bulianta coal and high rank Qinshui coal, the swelling effect induced by CO2 is dominant. Thus, the moisture content after CO2 interaction decreases in comparison with the raw state.

Improving the Estimation Accuracy of Copper Oxide Leaching in an Ammonia–Ammonium System Using RSM and GA-BPNN

In this study, a response surface methodology (RSM) model was used to analyze and optimize the factors affecting copper leaching efficiency in a copper oxide ammonia-ammonium (AA) system based on the parameters of AA concentration (ammonium hydroxide and ammonium bicarbonate matched with 1: 1), leaching time, grinding fineness, liquid-solid ratio, and temperature. The RSM analysis showed that five individual variables had a significant influence and that the interaction between AA concentration and leaching time had the most significant influence on leaching efficiency. In order to improve the estimation accuracy of the copper leaching efficiency, a model consisting of a genetic algorithm and a back propagation neural network (GA-BPNN) was used to optimize the operation index. A back propagation feed forward neural network with 3 layers (5–10–1) was applied to predict copper leaching efficiency. The genetic algorithm was applied to analyze the optimal leaching conditions. The results revealed that the GA-BPNN model outperformed the RSM model for predicting and optimizing copper oxide AA leaching. The optimization results of the GA-BPNN resulted in an R2 of 0.99827 and the highest predicted copper leaching efficiency of 79.49% was obtained under the conditions of an AA concentration of 4.78 mol/L, a leaching time of 157 min, a grinding fineness of 86.86% (–74 μm content account), a liquid-solid ratio of 2.87: 1, and a temperature of 313.17 K. A prediction and optimization method combining RSM and GA-BPNN, as used in this paper, can be further employed as a reliable and accurate method for ore leaching.

Ammonia Leaching Study on Carbonate Oxidised Copper Ores in Yunnan

The effects of oxidized copper ores which came from Yunnan province were carried out by using ammonialeaching methods in the laboratory.In order to seek the optimum leaching conditions under normal temperature and pressure,we conducted a series of validation experiments. Theoptimum conditions were obtained as follows: ammonia concentration 2.5mol/L, ammonium sulfateconcentration 2.5mol/L,grinding fineness about 80% -0.074mm, liquid-solid ratio 2.5:1and leaching time was 2.5h. Under these experimental conditions, the copper leaching rate could reach 69.91%.

Experiment on Recovery of Multi-Metal from Zinc Volatile Kiln Slag in Xining

For the comprehensive recovery of copper, zinc, silver and iron from the zinc volatile kiln slag in Xining, exploratory experiments were conducted by adopting single flotation, magnetic separation and combined process of magnetic separation and flotation. The results showed that the above process cannot effectively recover copper, zinc and silver from the ore. The recovery of iron is better by single magnetic separation. The grade of iron concentrate reaches 69.05% and the recovery is 41.86%.

Experimental investigation on flotation of refractory copper oxidized ore

To improve the recovery of copper from refractory copper oxidized ore by sulfidization-flotation process. The result determined the optimal flotation process parameters of refractory copper oxidized ore, and the better quota selecting separately obtained by a large number of research. The copper concentrate grade reaches 10.85%, the recovery reaches 57.41%.

Flotation of Sulphide Copper Ore of Sifangjing in Huidong

Flotation experimental research is carried out on a certain sulphide copper ore of Sifangjing in Huidong, Sichuan province. The ore exist in the deeper part of ore deposit. Because of the deep burried, the oxidation rate is relatively low. The ore belongs to the typical sulfide ore. For the characteristics of the mine and the scene of the test requirements, the use of direct flotation process has achieved a successful recovery of copper. In the cleaning operation ,Strengthen copper sulfur separation to obtain qualified copper concentrate. Under the proper process conditions ,the good technical indexes were obtained.

Research on Flotation of Copper Sulfide Ore in Yunnan Province

Floatation experimental research is carried out on a certain complicated ore containing mixed sulphides in Yannan province. For the characteristics of the mine and the scene of the test requirements, the use of mixed flotation-separation process has achieved a successful recovery of useful elements. Combination inhibitors can effectively achieve the separation of copper and sulfur .Under the proper process conditions ,the good technical indexes were obtained.