Abstract Molybdenum is often associated with nickel-tungsten based spent HDS catalyst and must be removed from tungstate solution to obtain commercially acceptable tungsten products. In order to address this problem, a different approach has been proposed in the present work. A two step process based on selective thionization of Mo using Na2S at alkaline condition followed by W precipitation as calcium tungstate (CT) using lime (Ca(OH)2) was studied. Various operating parameters were tested and optimum conditions for Mo thionization and W precipitation were developed. The CT produced by the conventional process was used as a reference to check the improvement in the proposed process with respect to Mo impurity. Under the optimum conditions, 92.7% Mo was rejected to the CT filtrate and 99.7% W converted to CT. The CT obtained from the proposed process contained 0.53% Mo, which was much less as compared to the CT obtained from the conventional process having 2.5% Mo using the same leach solution. High-grade ammonium paratungstate (APT) containing

中文翻译：

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从废钨钼催化剂碱性浸出液中回收高品位钨酸钙的工艺开发

摘要 钼通常与镍钨基废 HDS 催化剂有关，必须从钨酸盐溶液中去除才能获得商业上可接受的钨产品。为了解决这个问题，在目前的工作中提出了一种不同的方法。研究了基于在碱性条件下使用 Na2S 对 Mo 进行选择性硫离子化，然后使用石灰 (Ca(OH)2) 以钨酸钙 (CT) 形式沉淀 W 的两步法。测试了各种操作参数，并开发了硫离子化和钨沉淀的最佳条件。传统工艺产生的 CT 被用作参考，以检查所提出的工艺在 Mo 杂质方面的改进。在最佳条件下，92.7% 的钼被排除在 CT 滤液中，99.7% 的 W 转化为 CT。从所提出的工艺中获得的 CT 含有 0.53% 的 Mo，与使用相同浸出溶液从具有 2.5% Mo 的常规工艺中获得的 CT 相比，这要少得多。高品位仲钨酸铵 (APT) 含