Scheelite Concentrate Extraction from Tungsten Iron Ore

The existing technology of non-standard materials with low tungsten content is treated by traditional reverberatory furnace or rotary kiln sodium roasting. But roasting has the disadvantages of large consumption of roasting agent, low degree of automation, high energy consumption, low efficiency, high cost, large dust, low recovery rate and great influence on the environment. In the increasingly stringent environmental protection requirements, the development of tungsten iron ore seems to have no future.

Recently, however, some scholars have provided a process for extracting scheelite concentrate from tungsten iron ore or tungsten containing waste residue. This process is expected to meet industrial production. It includes the following steps:

(1) After smashing the tungsten iron ore into a particle size of -100, the particle mass content is not less than 80%, and the mixture of soda, compound salt and circulating tail liquid I is mixed uniformly with the mass ratio 1:0.2:0.15:0.2, and the mixture is pressed to get the flat round pellets with a diameter of around 43mm.

(2) The pellets were calcined in the vertical kiln by gas roasting, and the temperature was calcined at 750°C for 1.6h. After roasting, the pellets were cooled and added to the circulating tail liquid I at room temperature, the grinding was carried out at the same time. The solid particle content of the solid particle size of -100 was not less than 75%, and the leaching time was 1H, at the same time, by controlling the addition of I in the circulating tail liquid, the leaching slurry is obtained by adjusting the pH of the leaching system at about 9.5. The leaching slurry is filtered and separated, and the leaching residue of sodium tungstate and leaching residue is mainly composed of iron and other valuable metals, which can be used to prepare iron concentrate or to recover other valuable metals.

(3) The sodium tungstate leaching solution obtained by filtration is adjusted to about 3.2 pH. As a liquid phase, the large aperture weak alkaline anion resin D314 is used as the stationary phase of the ion exchange column, and the ion exchange column is adsorbed and separated. After the adsorption separation is completed, the fixed phase is eluted with the NaOH solution of the mass percentage of 10%.

(4) NH₄Cl:MgCl₄ = 1:2.5 was added to the sodium tungstate enrichment solution, and the mixture was added to 10 kilograms per meter of liquid to precipitate, and the precipitates were precipitated by filtration; calcium chloride precipitator was added to the filtrate to precipitate and crystallize, and then filtered and separated to obtain the scheelite concentrate and tail liquid; the tail liquid was used as the tail end. The liquid II returns to the resin adsorption separation process of step three to recover a small amount of tungstate ion.

(5) After the separation of the ion exchange column, the flow phase adsorbed the residual liquid. When Na+ < 30g/L, as the circulating tail liquid I return to the ball making process and the process of grinding and leaching, when the residual liquid Na+ is more than 30g/L, adding ferrous chloride, the amount of ferrous chloride is about 3.5kg/m3, and the alkali lime is added to maintain the pH at the reverse end point of about 7.5, and flocculation is carried out. Precipitation, filtration and separation, the salt solution is evaporated and crystallized to get the compound salt crystal used in step one. The crystallization mother liquid is used as the circulating tail liquid I to return to the grinding and leaching process.

This process can effectively separate high grade Scheelite Concentrate from tungsten ores with low tungsten grade or tungsten waste residue. This process has low energy consumption, low production cost, low pollution discharge, friendly environment, high efficiency and comprehensive utilization of resources to meet industrial production.

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