Study On Roasting Properties Of High Phosphorus Rhodochrosite And Process Of Roasting-Ammonia Leaching

There are abundant reserves of rhodochrosite in Cheng Kou and Wan Yuan area. However, the characteristics of rhodochrosite in Cheng Kou and Wan Yuan is complex, fine grain size, low manganese grade, containing high phosphorus and silica, useful minerals and gangue close intergrowth. The existing technology is difficult to produce qualified manganese concentrate products. Therefore, this paper take advantage of high dephosphorization and ammonia recycling in the process of roasting ammonia leaching. Aimed at Cheng Kou and Wan Yuan manganese ore, focusing on the process of roasting process to carry out the system research, and combined with roasting- ammonia leaching process design and feasibility of the experimental results is analyzed, for roasting- ammonia leaching process to achieve large-scale production to provide the basis.This article first through the thermodynamics analysis, the result showed that MnCO₃, MgCCO₃ and CaCCO₃ thermodynamic starting reaction temperature were 622.7K, 913.3K and 1183.1K. In CCO₂ atmosphere, with the increase of CCO₂ partial pressure, start decomposition temperature of MnCO₃ is increase. Thermogravimetric experiments verify that the flow under the 200ml/min, under the CCO₂ condition, the decomposition reaction temperature of MnCO₃ was increased by about 40 degrees compared to the condition of N₂.Then using thermogravimetric analysis technology to research decomposition mechanism of manganese ore for Cheng Kou and Wan Yuan. Study mainly used multiple scan rate（FWO, Kissinger and Friedman） and single sweep rate method to determine pyrolysis mechanism function and kinetic parameters. The research results show that the most probable mechanism model of Cheng Kou and Wan Yuan manganese ores is random nucleation model, reaction control steps are chemical reactions. Cheng Kou manganese, the average activation energy E and pre exponential factor lg A of MnCO₃ decomposition are 208.19KJ/mol and 11.12 respectively. Wan Yuan manganese, the average activation energy E and pre exponential factor lg A of MnCO₃ decomposition are 237.52KJ/mol and 12.29 respectively, compared with the Chengkou manganese ore, activation energy and pre exponential factor of Wan Yuan manganese ore were higher.In this paper, the roasting dynamic analysis of constant temperature was done, the results show that the decomposition reaction’s control steps of Cheng Kou rhodochrosite is chemical reaction, the reaction rate equation:The decomposition reaction’s control steps of Wan Yuan rhodochrosite is chemical reaction, the reaction rate equation:In addition, the optimum conditions for roasting effect of manganese ore were determined, through the experiment of roasting, the experiment of activity degree and the method of the combination of ammonia leaching experiment. Cheng Kou manganese ore: Particle size control in 0.25<d<3mm, the reaction in the N₂ atmosphere, temperature control at 650℃, roasting about 100 min, in this condition, The activity of the roasted ore was the best and the leaching rate of Mn was the highest, which could reach about 74%. Wan Yuan manganese ore: Particle size control in 0.25<d<3mm, the reaction in the N₂ atmosphere, temperature control at 650℃, roasting about 60 min, in this condition, The activity of the roasted ore was the best and the Mn leaching rate was the highest, which could reach about 81%.