CS260150B1 - The method of cleaning the extract from tungsten ore - Google Patents

Abstract

Sufficient cleaning effect by adding a precipitating agent and the formation of a well-filterable precipitate, which removes only a very small part of the tungsten, is achieved by using a solution containing both ferric and magnesium salts in a weight ratio of iron and magnesium of 20:80 to 70:30.

Description

The invention relates to a method for purifying a tungsten ore leachate containing tungsten in the form of sodium tungstate by adding iron and magnesium salts to this leachate at a pH of 9 to 11 and separating the resulting precipitate from the liquid phase of the leachate.

To purify the leachate from tungsten ore from arsenic and phosphorus, iron or magnesium salts are used. As a rule, most of the silicon is removed from the leachate by adjusting the pH to about 3 to 9 and filtering off the precipitated silicic acid. Then, at a pH of 9 to 11 and usually at a temperature above 60 °C, a magnesium salt, such as magnesium sulfate or chloride, or a ferric salt, such as ferric chloride, is added to the leachate, and optionally the pH is adjusted again by adding sodium hydroxide or carbonate to the above range. The action of magnesium salts is very effective and the loss of tungsten in it usually does not exceed 1%. However, the precipitate is very fine and hardly settles, so it is necessary to filter the entire volume of the leachate. Filtration is difficult and slow and cannot be done without the use of auxiliary filter media. Precipitation with ferric salts is not as effective as precipitation with magnesium salts, but relatively filterable precipitates are formed. The disadvantage of using ferric salts is the large loss of tungsten.

The above-mentioned disadvantages are eliminated by the method of purifying the leachate from tungsten ore containing tungsten in the form of sodium tungstate by adding iron and magnesium salts to this leachate at a pH of 9 to 11 and separating the precipitate formed from the liquid phase of the leachate according to the present invention. This method consists in adding to the leachate an aqueous solution containing magnesium chloride, sulphate or nitrate and at the same time chloride, sulphate or ferric nitrate in a weight ratio of iron and magnesium of 20:80 to 70:30. The method according to the invention is preferably carried out in such a way that the solution of the ferric and magnesium salts is mixed with an aqueous solution of ammonia before being added to the leachate. The advantage of the method according to the invention is a good purifying effect, as well as good filterability of the precipitate and low tungsten losses. This effect cannot be achieved by any of the previously known processes, nor even when ferric and magnesium salts or their solutions are dosed into the leachate separately.

Examples 1 to 3 ml of a tungsten ore leachate (154 g/l tungsten oxide WO3, 0.050 g/l silicon dioxide SiO^, 0.160 g/l arsenic As, 0.060 g/l phosphorus P) are heated to 80 °C, the pH is adjusted to 10.5, 1 ml of a solution containing 250 g/l magnesium chloride hexahydrate MgC^.éHgO and/or ferric chloride hexahydrate FeCl^.óHgO is added and after 2 h of stirring the resulting precipitate is separated by filtration through a filter cloth. The results are summarized in Table 1 below. Examples a), b) and c) are for comparison. In example c) 0.5 ml of ferric chloride solution was first added and then the same amount of magnesium chloride solution.

Note: After filtering the sample from experiment a) through a paper filter with blue tape without using pressure, the SiO ₂ content in the filtrate was 0.01 g/1, As 0.045 g/1. In all other cases, vacuum was used during filtration, but the precipitate from experiment a) also passed through a paper filter with blue tape during vacuum filtration.

Table 1 ratio appearance of the filtrate impurity content(g/l) losses W (%) No. Fe Mg ^Si0 2 As P a, 0 100 turbid 0.03 0.11 0.05. 0.9 1 20 80 slightly cloudy 0.02 0.07 0.04 1.1 2 50 50 clear 0.02 0.05 0.02 0.95 3 70 30 clear 0.02 0.06 0.02 1.3 b; 100 0 clear 0.05 0.09 0.05 2.8 c 50 50 turbid 0.04 0.12 0.06 1.8

Example 4

To 100 ml of the extract (same as in examples 1 to .3) at 80 °C and pH 10.3, 3 ml of a solution containing 37.5 g/l FeCl6HgO and 212 g/l MgC^.6HgO are added. After 2 E of stirring, the extract is allowed to settle until more than 60% of the volume is clarified. Then 60% of the volume is decanted and the remainder is filtered through a filter cloth (filtrate I) and part of it through a blue tape filter paper (filtrate II·). 0.035 g/l As was found in the decantate, 0.049 g/l As in the filtrate I and 0.032 g/l As in the filtrate II. The average As content in the solution after combining the decantate and filtrate I is 0.041 g/l.

Example 5

To 150 ml of the leachate (137 g/l WQ^, 0.50 g/l Si0 ₂ , 0.26 g/l As, pH 8.9) at 60 °C is added a mixture prepared by mixing 5 ml of a solution containing 62 g/l FeC1^.6H ₂ 0 and 188 g/l IvIgClg.6H^O with 2 ml of concentrated aqueous ammonia solution. After 2 h of stirring, the leachate is filtered through a filter cloth. The filtrate contains 0.024 g/l SiO ₂ ^and θ>°6ΐ g/l As. The WO^ losses are 0.7%.

Claims (2)

A process for the purification of a tungsten ore extract containing sodium tungstate by adding iron and magnesium salts to the extract at pH 9 to 11 and separating the resulting precipitate, characterized in that an aqueous solution containing magnesium chloride, sulfate or nitrate is added to the extract; at the same time ferric chloride, sulphate or nitrate in a weight ratio of iron to magnesium of 20 to 80 to 70: 30. 2. Method according to point 1? characterized in that the solution of ferric and magnesium salts is mixed with an aqueous ammonia solution prior to addition to the leachate.