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通过热力学计算得出温度为800,900 K时,不同Mo S2,Ca O,O2初始物质量条件下对应Mo S2-Ca O-O2体系的热力学平衡,确定辉钼矿石灰焙烧的反应机制。热力学分析表明,800 K时体系初始摩尔量Mo S2∶Ca O=1∶3时,随着氧用量的增加Mo(VI)优先与石灰、氧气结合生成CaMoO_4,然后S(II)被氧化生成CaSO_4,体系氧化最终热力学平衡产物为CaSO_4,CaMoO_4;800 K时体系初始摩尔量Mo S2∶Ca O=1∶2时,随着氧用量的增加,约70%的Mo S2首先生成CaMoO_4,Ca S,然后Ca S氧化为CaSO_4,最终CaMoO_4作为固硫剂与残余的Mo S2反应生成Mo O3和CaSO_4,最终对应热力学平衡产物为CaSO_4,Mo O3。理论上证明可以实现辉钼矿选择性钙化焙烧;温度从800 K提高至900 K时,不影响全钙化焙烧过程;对于选择钙化焙烧高温不利于CaMoO_4固硫,而富氧益于固硫。验证试验采用100 g辉钼矿与55 g氧化钙混匀,在温度为800 K的马弗炉中焙烧2 h,焙砂钼、硫固定率分别为98.36%,91.44%,X射线衍射(XRD)分析表明钼硫分别以Mo O3,CaSO_4存在,与热力学分析结论一致。
The thermodynamic equilibrium of Mo S2-Ca O-O 2 system with different Mo 2 O, Ca O and O 2 initial mass at 800,900 K was obtained through thermodynamic calculation to determine the reaction mechanism of limonite calcination. Thermodynamic analysis showed that Mo (VI) preferentially combines with lime and oxygen to form CaMoO_4, and then S (II) is oxidized to CaSO_4 as the initial molar Mo S2: CaO is 1: 3 at 800 K , And the final thermodynamic equilibrium product of the system is CaSO 4, CaMoO 4. When the initial molar amount of Mo 2 O: Ca O is 1: 2 at 800 K, about 70% of Mo 2 O first produce CaMoO 4, Ca S, CaS is oxidized to CaSO_4, finally CaMoO_4 acts as a sulfur-fixing agent and reacts with residual Mo_2 to form MoO3 and CaSO_4. The final thermodynamic equilibrium products are CaSO_4 and MoO3. It is theoretically proved that the selective calcination roasting of molybdenite can be realized. When the temperature is raised from 800 K to 900 K, the calcination without calcining is not affected. In the verification test, 100 g molybdenite and 55 g calcium oxide were mixed and calcined in a muffle furnace at a temperature of 800 K for 2 h. The calcine molybdenum and sulfur fixation rates were 98.36% and 91.44%, respectively. The X-ray diffraction ) Analysis showed that molybdenum and sulfur were present as MoO3 and CaSO_4 respectively, which was consistent with the conclusion of thermodynamic analysis.