以硫化锌精矿为研究对象,采用富氧-硫酸浸出的方式提取矿物中的锌元素并使硫元素以单质的形态进入浸出渣中,考察浸出粒度、温度、初酸浓度、氧分压对酸浸过程动力学的影响。研究结果表明:硫化锌精矿的浸出过程由表面化学反应控制,反应遵循"未反应核收缩模型"的表面化学反应控制的动力学规律,其反应活化能E=73.58 k J/mol。
Carbonation decomposition of hydrogarnet is a significant reaction of the calcification-carbonation new method for alumina production by using low-grade bauxite.In this work,non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution was studied by high-pressure differential scanning calorimetry(HPDSC) at different heating rates of 2,5,8,10,15 and 20 K·min^(-1),respectively.The activation energy(E_α) was calculated with the help of isoconversional method(model-free),and the reaction mechanism was determined by the differential equation method.The calculated activation energy of this reaction was 115.66 kJ·mol^(-1).Furthermore,the mechanism for decomposition reaction is Avrami-Erofeev(n=1.5),and the decomposition process is diffusion-controlled.
Red mud produced in the Bayer process is a hazardous solid waste because of its high alkalinity; however, it is rich in valuable components such as titanium, iron, and aluminum. In this study, a novel calcification–carbonation method was developed to recover alkali and alumina from Bayer red mud under mild reaction conditions. Batch experiments were performed to evaluate the potential effects of important parameters such as temperature, amount of CaO added, and CO_2 partial pressure on the recovery of alkali and alumina. The results showed that 95.2% alkali and 75.0% alumina were recovered from red mud with decreases in the mass ratios of Na_2 O to Fe_2O_3 and of Al_2O_3 to Fe_2O_3 from 0.42 and 0.89 to 0.02 and 0.22, respectively. The processed red mud with less than 0.5wt% Na_2 O can potentially be used as a construction material.
