Phosphorus Removal Slag Processing in Tungsten Smelting

At present, with the shortage of tungsten mineral resources, especially the rising price of tungsten products in recent years, the rational comprehensive utilization of tungsten-containing phosphorus removal slag produced in the production process of ammonium paratungstate (APT) can not only create profits for the reuse of enterprise resources, but also create wealth for the country.

With the continuous optimization of APT process for scheelite production, new scheelite decomposition technology has gradually replaced hydrochloric acid decomposition, sodium carbonate decomposition, caustic sodium decomposition and other wet smelting technologies, and has become the mainstream process for Scheelite decomposition. With the basic objectives of high decomposition rate, low alkali consumption and environmental protection, the process achieves low-alkali and high-efficiency decomposition of all scheelite.

A method for treating phosphorus removal slag in tungsten smelting is to immerse the phosphorus removal slag produced in the dephosphorization process of ammonium paratungstate production into aqueous solution with a liquid-solid quality ratio of 4:1. After adding leaching agent and activator, the decomposition slag and decomposition solution of phosphorus removal are filtered into the decomposition solution after full reaction in the reactor, and the valuable metal tungsten is entered into the decomposition solution as described in sheet alkali. The activating agent is 85 wt% phosphoric acid, and the amount of tablet alkali and phosphoric acid is enough to make the WO₃ reaction in phosphorus removal residue produce Na₂WO₄. The specific operation is as follows:

The treated phosphorus removal residue contains WO₃ 20.67%, the wet weight of phosphorus removal residue is 1035 Kg, the moisture content is 50%, and the dry weight is 517.5 Kg.

First, the phosphorus slag is poured into the return slag tank and stirred with water. The liquid-solid ratio of water to slag is controlled at 4:1. After uniform mixing, the material liquid is poured into the intermediate tank and stirred. First, 100 cm of water is added into the alkali solution tank, 79 kg flake alkali is added. After uniform stirring, the residual alkali in the alkali solution tank is fully stirred.

The residual alkali in the alkali solution tank is cleaned with clean water, and 66 Kg 85% industrial phosphoric acid is added to the intermediate tank. Wash the residual acid in the alkali-dissolving tank with water; feed the material into the reactor after dispensing and react fully; the reactor is heated to 180 ℃ for 2 hours, and then discharge the material to the dilution tank. The decomposition liquid contains tungsten metal and is used for subsequent preparation and extraction. The decomposition slag is washed after filtration; the washing water is soft water from industry; the decomposed phosphorus slag is filtered; and the decomposed phosphorus slag is filtered. The content of tungsten is 0.85%, wet weight is 900 Kg, moisture is 50%, dry weight is 450 Kg. The amount of tungsten in decomposed phosphorus slag is 3.83 Kg, and the leaching rate of tungsten in phosphorus slag is over 96%.

This process can effectively treat phosphorus removal slag with low consumption, and effectively recover valuable metals in the slag to prepare APT, and comprehensively utilize resources. Consumption control is 0.6-0.8 times of theoretical quantity. It can save energy and cost. It can also be a good reference for tungsten smelting industry to deal with low-grade raw materials.

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