CS199373B1 - Method of transforming lithium and other alkaline metals from silicate ores and concentrates in water-soluble form - Google Patents

Description

(54) A method for converting lithium and other alkali metals from silicate ores and concentrates to a water-soluble form

The present invention relates to the conversion of lithium, potassium, rubidium and cesium from silicate ore concentrates of the spodumen, lapidolite, potalite, quartzite, etc. type into a water-soluble form by calcination with additives and subsequent leaching.

Lithium and its compounds play an increasingly important role in industry. Most of the lithium raw materials under which the lithium compounds are obtained are ores of the silicate type. A number of technological processes have been proposed for converting lithium into a water-soluble form. The wet processes in which 8β uses sulfuric acid are suitable for single spodumen ores. However, the method using sulfuric acid to decompose the lithium mineral is not suitable for ores containing more iron than lithium oxide because of the difficulty in separating the solution obtained.

For fluorine-containing lithium ores, the sulfuric acid digestion method is also poorly suited to corrosion problems.

Therefore, dry decomposition processes are more industrially widespread in which the lithium ion is displaced beyond the silicate lattice and is thus converted into a water-soluble form by alkali metal ions or by alkaline earth ions.

For example, when using potassium sulfate, an emission of 10 wt. parts of lithium ore with 3 to 5 wt. parts of potassium sulfate. When limestone is used, 10 wt. parts of ore with 30 to 35 parts by weight of limestone. 3, decomposition methods are described in which a DC of 10 wt. parts of the ore were mixed with 10-15 wt. parts of sulfate and calcium oxide. Calcination of the mixture at temperatures of 800 to

199 373

1100 ° C and transforms the lithium into a water-soluble form. The potassium process requires potash for the isolation of lithium carbonate, the calcium sulfate process also requires potash, and the limestone process is costly in energy, or? the amount of mass which should have been heated to a temperature of at least 900 ° C is three to four times the towed ore charge.

The above disadvantages are overcome by the process of converting lithium into the water-soluble form of the invention. Based on the fact that the lithium ore ore concentrate is mixed with magnesium oxide or magnesium carbonate or with dolomite in a weight ratio of 1: 0.5 to 1: 2.5, the mixture is ground and calcined at 800 ° C to 1100 ° C, rapidly cooled to less than 500 ° C over 10 to 30 minutes and then leached. . Barium ions are as effective as potassium ions with respect to virtually identical ionic radius. The theoretical presumption of their substitution in the silicate lattice has been confirmed by experiments in which the efficacy of sulfur, nitrate and magnesium chloride in particular has been shown to be high.

By the process according to the invention, lithium can be obtained economically with no lower cost of magnesium raw materials. Another advantage is fuel savings in calcination and easier isolation of lithium from leaching solutions. This makes it possible to use raw materials or concentrates with a lower lithium content.

However, the use of soluble magnesium salts is practically impeded by similar chemical behavior of the two elements, so that separation from the solution is expensive. This disadvantage can be eliminated by using the present invention insoluble magnesium aloučanin, in particular magnesium oxide MgO, magnesium carbonate double MgCOg aebo carbonate hořečnatpvópenatého MgCa (C0 _{3) 2,} which occurs naturally as the mineral dolomite industrially exploitable bearings.

For example, parts by weight of lithium ore were mixed with the decomposition component, the mixture was ground in a ball mill and then calcined at 920 ° C for 20 minutes, then cooled to between 50 ° C and 350 ° C over 10-20 minutes. After cooling completely, the calcined salt was taken up in a total of 250 ml of water in three portions and the combined extracts were filtered and evaporated. The total yield was calculated by determining the lithium content

20 May 9 red and 60 9 CaC0 ₃ yield 67 % 20 May 9 red and 50 9 dolomite yield 73 % 20 May 9 red and 40 9 MgCOg yield 74 % 20 May 9 red and 25 9 MgO yield 78 % 20 May 9 red and 20 May 9 MgO yield 76 %

Experiments have shown that using magnesium oxide, magnesium carbonate or dolomite can take advantage of the decomposition benefits of the lithium ore 8 limestone firing method, particularly as regards the easy isolation of lithium hydroxide LiOH and lithium carbonate Li ₂ CO ₃ . Since thermal decomposition of magnesium carbonate and / or dolomite starts at a lower temperature and requires less heat than thermal decomposition of calcium carbonate, the use of dolomite or magnesium carbonate or magnesium oxide as

199 373 decomposition components reduce fuel costs compared to using calcium carbonate for the same purpose. By replacing the limestone with dolomite or magnesite or magnesium oxide, an increase in the ore component of the furnace during firing can also be achieved, as a result of the reduction in the weight of the decomposition component.

In the silicate lithium raw materials, potassium, rubidium and cesium are also released into the water-soluble form in the process according to the invention, which can be obtained for further use after separation of the lithium from the solution. If fluorine is present in lithium ore, it is bound in the calcine as MgF ₂ and thus does not reduce the yields of lithium.

Claims (1)

OBJECT OF THE INVENTION Process for converting lithium and other alkali metals from silicate ores and concentrates to a water-soluble form, e.g. in a weight ratio of 1: 0.5 to 1: 2.5, the mixture is ground and calcined at 800 to 1100 ° C, cooled rapidly to less than 500 ° C within 10 to 30 minutes, preferably below 100 ° C, and then puddle.