【作者】 谷晋川；

【导师】 张允湘；

【作者基本信息】 四川大学 ， 化学工艺， 2003， 博士

【摘要】 矿物深加工及制品是当今国际非金属行业发展的主要趋势，利用微波特性提纯硅藻土矿是矿物深加工的一种新方法。本论文以硅藻土矿为研究对象，开展“微波强化硅藻土矿提纯机理研究”，探讨微波对硅藻土矿酸浸提纯反应的影响规律。 实验表明硅藻土矿、硫酸溶液和水在微波作用下温度升高。研究发现硅藻土矿的升温和纯金属矿物的升温有所不同，硅藻土矿的升温不存在“失控现象”；硅藻土矿在微波场中的升温过程可分为线性升温期、对数升温期两个阶段，可采用一元三次多项式来描述；水和硫酸溶液在微波场中的升温行为可用一元二次多项式来描述。研究发现微波场中水和硫酸稀溶液的电导率均高于常规条件下的电导值，微波对水和硫酸稀溶液存在“非热效应”。 微波提纯机理研究表明：在微波场中的矿粒在电磁场作用下其内部形成传导电流，发生电子积聚，有利于克服禁带宽度；矿浆体系中的粒子或溶液离子在微波场作用下发生转动和取向极化，促进电子的交换。同时微波能使矿粒产生裂纹、比表面积增加、使药剂深入矿粒内部、增加反应机会，提高反应体系液相物质的电导率、提高了矿浆的温度，促进反应的进行。 通过理论分析和数据处理，建立了微波和加热作用下硅藻土矿稳态酸浸提纯的动力学模型： 微波： 常规：式中:T一反应温度，K;x一硅藻土矿铁的浸出率，%;t一反应时间，s;R-摩尔气体常数，8.314)/(mole.K)。 微波和常规加热作用下化学控制阶段的活化能分别为59.OSKJ/mol和28.49KJ/mol，频率因子之比为Kl。/K常0=77049.24;混合控制阶段的活化能分别为In.09 kJ/mol和64.63 kJ/mol。微波场作用虽然使化学反应的活化能升高，但是使频率因子大大增加，施加的微波场从抑制和促进反应两方面影响反应体系，最终增大了化学反应速率。实验结果表明微波作用下硅藻土矿稳态酸浸速率是常规作用的3一10倍。 结合工业生产实际，开展了微波非等温浸出过程研究，建立了硅藻土矿酸浸提纯的反应动力学模型。 In[(1一x)‘，/(n一1)1 =In[(A po-，)·(E’/R)〕一2.314一0.4567(E/RT) A二一2X10-s w3+0.0137w2一2.8785w+199.76 E== 0.0586w3一25.693w2+2854.4w+18831 p二e叮伪，E，=E+aR，p。二e‘ a=一0.0033w3+1.5138w2一207.08w+11128 b二10一3一0.0047犷+0.6614贮34887 式中:n=2/3;E、E’为反应活化能，J/mole;x为硅藻土矿铁的浸出率，%;T为反应体系的温度，K;，为微波作用功率，W;A为频率因子;p为升温速率:a，b为与微波功率w有关的温度常数。 研究发现在不同微波功率的作用下，反应体系的升温速率是时间的函数，升温速率与温度呈非线性关系;发现微波对化学反应的影响是非线性关系，微波作用可以改变反应的活化能和频率因子，随着微波功率的增加，反应的活化能和频率因子降低，降到一定程度后，反应的活化能和频率因子升高。 研究提出了硅藻土微波提纯新工艺，通过实验确定了硅藻土微波酸浸提纯工艺的较佳工艺条件:硫酸浓度飞既，浸出时间45分，微波功率26湃，这为微波技术在矿物工程、冶金工程领域的应用奠定了一定的基础.关键词:微波;非金属矿;硅藻土;提纯;反应;工艺;动力学更多还原

【Abstract】 The main trend in modern non-metallic mineral industry is deepening processing for minerals and production of these products. It is one of new methods on mineral deepening for using microwave technology to purify diatomite .We decided on adopting diatomite in this paper, performing "the study on the mechanism in purification of diatomite ore by microwave strengthening" then probing into the regular patterns on purification of diatomite processing by microwave strengthening.The results of the experiment indicated that temperature of diatomite ore and water and diluted sulfuric acid solutions would raise in microwave field. We found that raising temperature of diatomite is different from that of pure metallic minerals, has not "getting out of control " phenomenon; raising temperature process of diatomite in microwave field can be divided into two stages ie. linear raising temperature period and logarithmic one, and can be described by onespot third order multinomial. Raising temperature behavior of water and sulfuric acid solutions in microwave field can be described by onespot second order multinomial. Investigation found that the conductivity of water and diluted sulfuric acid solution both are higher than conductivity in conventional condition and microwave has a "non-heating effect" for water and diluted sulfuric acid solutions.The results of the researches on the mechanism on purification of diatomite ore by microwave strengthening indicated that conductible current in diatomite particles was formed and electrons were accumulated under electromagnetic fieldaction, this is advantageous to overcome the width of forbidden band; particles or solution ions in pulp system take place turn and orientation polarization, therefore promote electrons exchange and reaction; at same time, microwave can result in mineral particles cracking, specific surface area rising, reagents entering interior of mineral particles, increasing reaction opportunity, raising conductibility of liquid matter in reaction system , raising pulp temperature, and promoting reaction going on.Based on theory and experiment research, kinetic model of isothermal stable state reaction of acid leaching purifying for diatomite was established.Microwave:Conventional :There, T is reaction temperature, K; x is leaching rate of iron from diatomite,% ; t is reaction time, s; R is molar gas constant, 8.314 J/(mole. K).Activation energies of chemical control for microwave action and conventional heating action are 59.05 KJ/mole and 28.49KJ/moIe respectively, frequency factor ratio Kmic/Kconv=77049.24. Activation energies of mixed control for microwave action and conventional heating action are 111. 09 kJ /mol and 64.63 kj/mol respectively, Under microwave field action, activation energy of chemical reaction increased, but frequency factor greatly increased, microwave field has influenced on reaction system by depressing and promoting and increased chemical reaction rate last. The results of the experiment indicated that the reaction velocity of microwave reaction is 3-10 times with that of conventional heating reaction.The study on non-isothermal leaching process was performed with industrial production, kinetic equation of acid leaching purifying for diatomite was established.there n=2/3; E or E’ is activation energy, J/mole; x is leaching rate of iron from diatomite, %; T is temperature in reaction system, K; w is microwave interaction power, W; A is frequency factor; is raising temperature rate ;a and b are temperature constants related with microwave power ,w.The investigation has indicated that raising temperature rate of reaction system with microwave is a function of time, the relationship between raising temperature rate and temperature is nonlinear; and has found that the influence of microwave on chemical reaction is a non-linear relationship. Activation energy and factor of reaction can be changed by microwave interaction, and decreased along with microwave power increases, after reaching to a certain degree, they raise.A new technology for purificati更多还原