【摘要】 因钼矿石浮选及预处理工艺不同，得到的钼精矿品位不同，导致钼精矿焙烧行为和热量释放区间存在差异。为了合理配矿以满足钼焙砂质量，需分析不同品位精矿焙烧行为及发热量。因此，本文利用热重差示扫描量热-质谱联用法（TG-DTG-DSC-MS）及发热量测定法分段研究了5种品位钼精矿焙烧过程中氧化和升华/挥发特性，并采用Coats-Redfern法研究了钼精矿品位对动力学参数的影响。结果表明：钼品位对氧化速率影响明显，钼品位由48%增大至56%时，对应的最大氧化速率由0.065 mg·min^-1增大为0.095 mg·min^-1；当焙烧温度由600℃升到630℃，钼品位为48%的精矿质量增加了6%。分别采用量热仪、差示扫描量热（DSC）曲线积分和热力学方法获得的发热量均与钼品位呈相关性方程。升华/挥发阶段（MoO₃挥发）因作用机制不同，主要分为3部分：第一部分（630～720℃）MoO₃开始升华；第二部分（721～870℃）MoO₃熔化、挥发；第三部分（871～1000℃）MoO₃二次挥发及不稳定钼酸盐分解。不同品位钼精矿氧化阶段活化能整体处于120～135 kJ·mol^-1，控制环节为界面化学反应。升华/挥发阶段钼品位在51%～56%的精矿活化能整体处于340～360 kJ·mol^-1，控制环节为形核和核生长；钼品位为在48%～49%的精矿活化能整体处于238～240 kJ·mol^-1，控制环节为内扩散。不同品位钼精矿搭配使用，合理利用高品位精矿前期的高发热量以实现低品位精矿氧化反应彻底进行，从而抑制MoO₃的大量挥发和烧结。更多还原

【Abstract】 China has abundant molybdenum resources, the majority of which are in the form of molybdenite, which has the highest industrial value. However, the grade and roasting behavior of molybdenum concentrate are different due to different subsequent flotation and pretreatment processes of molybdenum ore mined. To maintain the smooth progress of the reaction, external heat sources are still required for the industrial roasting of molybdenum concentrate. With the wide application of low-grade molybdenum concentrate, it has also brought many problems. It is simple to produce molybdate during the roasting of low-grade molybdenum concentrate, which is challenging to remove, if the temperature is too high or the roasting time is too long. The formed molybdate leads to the decrease of MoO₃ content. Low grade molybdenum concentrate has a high impurity component content, which hinders the concentrate’s ability to oxidize. The phenomenon of sintering takes place during the roasting process, leading to a high rate of residual sulfur and MoO₂ in the molybdenum calcine. Therefore, in order to meet the quality of molybdenum calcine, it is necessary to analyze the roasting characteristics and calorific value of various concentrate grades. In this study, five types of molybdenum concentrates processed from different production areas were selected, and the elemental composition and microstructure of the molybdenum concentrates were characterized by inductively coupled plasma（ICP） and scanning eectron microscope（SEM）. The characteristics of oxidation and volatilization in five different grades of molybdenum concentrate during roasting process were studied by simultaneous thermogravimetry-differential scanning calorimetry-mass spectrometry（TG-DTG-DSC-MS）, and the heat release characteristics and linear equations during the roasting process of molybdenum concentrate. Coats-Redfern method was used to calculate the activation energy of different grades of molybdenum concentrate and to determine the limiting step of the reaction in the oxidation/volatilization stage. The results showed that roasting process of molybdenum concentrate was divided into three stages. In the first stage（45～400 ℃）, the moisture and flotation agents in molybdenum concentrate began to volatilize. In the second stage（400～630 ℃）, MoS₂ oxidation to produce MoO₃ and SO₂.In the third stage（630～1000 ℃）, the formed MoO₃ began to undergo significant sublimation and volatilization. While molybdenum was in a different grade during the oxidation stage, this had no bearing on the temperature at which oxidation begins and finishes. The molybdenum grade had a significant effect on the oxidation rate. When the molybdenum grade increased from 48% to 56%, the corresponding maximum oxidation rate increased from 0.065 to 0.095 mg·min^-1. When the roasting temperature increased from 600 to 630 ℃, the quality of concentrate with molybdenum grade of 48% increased by 6%. Due to the presence of a large amount of impurity oxides in this grade of molybdenum concentrate, which combined with SO₂ to form sulfates. The calorific value measured by low grade molybdenum concentrate calorimeter was obviously less than the theoretical calorific value. The low-grade molybdenum concentrate contained a significant amount of impurity oxides in addition to the primary MoS₂ phase. The heat released by the impurity oxides during the reaction was 500 J·g^-1, which was much smaller than the heat value of MoS₂ oxidation. The calorific value obtained by calorimeter, DSC integration and thermodynamic method was correlated with molybdenum grade. The calorific value equation of molybdenum concentrate calculated by thermodynamics was y=17.74x-0.029, and the fitting degree was R²=0.99. The calorific value equation measured by calorimeter was y=239.36x-7273.91, and the fitting degree was R²=0.91. The calorific value equation y=35.29x-915.05 was obtained by DCS integration, and the fitting degree was R²=0.93. In industrial production, the heat generation during roasting could be effectively predicted based on the grade of molybdenum concentrate.The sublimation/volatilization stage was mainly divided into three parts due to different mechanisms of action: first step（630～720 ℃）was MoO₃ sublimate. Second step（721～870 ℃） was MoO₃ melting and volatilizing, and as a result of the eutectic reaction between the formed low melting point molybdate and MoO₃, the melting point of MoO₃ had decreased from the original 795 ℃ to about 750 ℃. At this temperature, MoO₃ melted significantly, which aggravated the volatilization of MoO₃. Third step（ 871～1000 ℃） was MoO₃ volatilizing and decomposition of unstable molybdate. The activation energy during the oxidation stage of different grade molybdenum concentrates was 120～135 kJ·mol^-1, and the control step of the reaction was interfacial chemical reaction. During the sublimation/volatilization stage, the activation energy of molybdenum grade with 51%～56% was 340～360 kJ·mol^-1, and the control step of the reaction was nucleation and nucleation growth, while the activation energy of molybdenum grade with 48%～49% was 238～240 kJ·mol^-1, and the control step of the reaction was internal diffusion. Different grades of molybdenum concentrate were used together, and the high calorific value of high grade concentrate in the early stage was used reasonably to realize the thorough oxidation reaction of low grade concentrate, so as to inhibit the volatilization and sintering of MoO₃.更多还原