Structure evolution of wolframite-type ZnZrC2O8 (C = Nb,Ta) ceramics in relation to microwave dielectric properties

The relationship among the sintering behavior, crystal structure, chemical bonding properties, and dielectric properties of wolframite-type ZnZr(Nb_1−xTa_x)₂O₈ (0.0 ≤ x ≤ 1.0) ceramics was investigated with the progressive replacement of Nb⁵⁺ by Ta⁵⁺. The optimum sintering temperature increases from 1225 to 1375°C with increasing Ta⁵⁺ content. The ε_r value falls from 27.34 to 22.34 due to a gradual decrease in bond ionicity and a shift in the Raman vibration modes toward higher wave numbers. The Q × f increases from 63 604 GHz (@6.71 GHz) to 115 631 GHz (@7.89 GHz), which is since the increase in the total lattice of chemical bonds. Moreover, the reduction in grain boundary area and the gradual lowering of the full width at half maximum of the Raman vibration modes contribute to the reduction in dielectric losses. First-principles calculations illustrate that the growth in bandgap and electron cloud density in the internal space of the [Zn/ZrO₆] octahedron leads to a reduction in dielectric loss. Furthermore, the reduced degree of oxygen octahedral distortion causes a change in τ_f from −46.56 to −37.40 ppm/°C.     

A new collector for wolframite slime flotation

With aniline and salicylaldehyde as main materials, a new collector for wolframite slime was synthesized. In a pulp of natural pH value, this collector can collect wolframite effectively. Its selectivity is similar to that of benzyl arsenic acid and better than that of sodium oleate. With this collector, a wolframite rough concentrate with grade 30.12 % WO3 and recovery 91.50 %, and a concentrate with grade 58.66 % WO3 and recovery 85.00 % were obtained respectively from a wolframite ore containing 4.08 % WO3.     

CARRIER FLOTATION OF ULTRAFINE PARTICLE WOLFRAMITE

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处理黑钨碱解渣制取碳酸锰

介绍了用硫酸浸取处理黑钨碱解渣，再氧化除杂，碳酸氢铵沉淀制取工业碳酸锰，并回收渣中黑钨矿的方法。     

湖南瑶岗仙黑钨矿床阶状交替成矿论

文章认真分析了瑶岗仙黑钨矿阶状交替派生断裂控矿的等级性和复杂性,阐述了阶状交替成矿模式的力学作用,为脉旁找脉、矿旁找矿和深部及周边外围找矿提供了理论依据。     

柿竹园黑白钨混合精矿常温浮选分离试验研究

对WO₃品位36%左右的黑白钨混合精矿进行了常温浮选分离试验研究。以氢氧化钠为调整剂、水玻璃和硫酸铝为组合抑制剂、CYW-29为捕收剂,采用一粗一精两扫浮选闭路流程,最终得到了WO₃品位30.30%、回收率38.68%的黑钨精矿和WO₃品位42.04%、回收率61.32%的白钨精矿。为期2个月的工业试验指标为黑钨精矿品位33.31%、回收率25.44%,白钨精矿品位40.78%、回收率74.56%,成功实现了工业应用,为同类型混合钨精矿常温浮选分离提供了借鉴。     

Leaching Systems of Wolframite and Scheelite: A Thermodynamic Approach

A linear correlation between free energy and enthalpy for crystalline and soluble oxocompounds based in the Sverjensky–Molling equation is used to calculate the Gibbs free energies of formation of MnWO₄ (?1172.48 ± 12.76 kJ mol^?1), H₂WO₄ (?1006.91 ± 10.36 kJ mol^?1), and Na₂WO₄ (?1455.39 ± 12.81 kJ mol^?1). Using these data with the known thermodynamic data, the equilibrium constants for reactions of leaching of scheelite and wolframite in acidic and basic media were determined. The results show that the acid route based in relatively cheap inorganic acids is desirable for scheelite digestion, despite the diffusion problems concerned with tungstic acid developed on the solid particles. Meanwhile, wolframite may be operated under favorable thermodynamics conditions by alkaline and acid processes.     

某低品位黑钨细泥浮-重-浮联合流程分选试验研究

对某低品位黑钨细泥,采用“预先脱硫浮选-离心机重选富集-黑钨细泥粗精矿再浮选”的工艺流程进行了选矿试验研究.试验结果表明,经二次浮选脱硫、一粗一扫离心机重选预富集、一粗三精二扫黑钨细泥粗精矿再精选的浮-重-浮联合工艺流程处理该黑钨细泥,最终可获得含WO3品位为38.01%、回收率为64.27%的钨精矿,较好地回收了该黑钨细泥中的钨矿物.该工艺由于采取了预先脱硫和离心选矿机的粗选富集措施,使整个浮选工艺药剂总用量大幅下降,更有益于节约选矿成本和环境保护.     

微细粒黑钨矿浮选研究现状

重选一直是黑钨矿选别的主要方法,但其对微细粒矿物分选的效果却较差,浮选法才是解决细粒级矿物分选的较好途径。近年来,我国微细粒黑钨矿浮选研究取得了一定进展,但生产实践方面仍存在不足之处。从微细粒黑钨矿的特点出发,简单介绍了微细粒黑钨矿的浮选新工艺、浮选药剂等,并讨论了它们各自的特点和适用性。并对近几年来微细粒黑钨矿相关浮选理论研究及矿物应用实例进行了综述,对钨矿山相关生产有一定的参考作用。     

钨矿表面特性与可浮性关系研究现状

钨矿选别过程中,黑、白钨矿分别主要采用重选法和浮选法回收.但因为重选难以高效回收微细粒黑钨矿以及浮选过程中白钨矿难以与含钙矿物有效分离等原因,导致钨矿回收率低或品位不理想.因此,有必要对黑、白钨矿的表面特性进行深入研究.介绍了黑、白钨矿表面特性的研究现状,主要评述了黑、白钨矿表面键的断裂、表面化学组成、表面异向性、表面电性以及表面溶解组分对钨矿可浮性的影响.对未来钨矿表面特性的研究方向和研究方法进行了展望.