RU2368681C1 - Recover method of uranium from hard ores - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes oxidising roasting at temperature 500-700°C and sulfuric acid leaching of uranium. For roasting it is subject crushed up to fineness - 2 or 5 mm ore, containing sulfur and carbonates. Received in the issue of roasting cinder is grinned, it is prepared from it pulp and it is used in scrubber for neutralisation of contained in effluent gas of roasting of sulfur dioxide. Neutralised pulp is taken out from scrubber and is directed to sulfuric acid leaching of uranium. Collected from effluent gas of roasting dust is granulated and granules are directed to roasting jointly with ore.

EFFECT: improvement of ecological situation at treatment of uranium ores, increasing of extraction ratio of uranium from ore ensured by efficient use of collected dust.

2 cl, 2 tbl, 1 ex

Description

The invention relates to methods for extracting valuable components from primary and mixed ores and can be used to extract uranium and related metals from hard-to-open ores.

Known methods for processing difficult to open uranium ores by leaching of metals in packs or autoclaves.

With traditional patchoumic leaching with sulfuric acid. / Pirkovsky S.A., Smirnov K.M. Autogenous autoclave technology is an alternative to the traditional leaching of uranium from hard-to-open ores. // Non-ferrous metals. 2003. No4. S.39-42. /; high uranium recovery is achieved if the process is carried out (temperature 60-65 ° C, 4 hours) in the presence of manganese dioxide at an acid flow rate of 205-340 kg / t ore (in terms of sulfur - 66.9 and 111 kg / t ore).

The disadvantage of this method is the high consumption of sulfuric acid, which leads to low profitability of the process.

Autoclave autogenous leaching. / Smirnov K.M. Development of technology for autogenous autoclave leaching of uranium from refractory ore raw materials: Abstract. dis.kand. tech. sciences. - M., 2007 / takes place at a pyrite flow rate of 167 kg / t in this embodiment (sulfur - 89.0 kg / t of ore), but eliminates the use of manganese dioxide.

Its main disadvantages are expensive equipment and the difficulty of selecting structural material for autoclaves.

The closest analogue is a method for extracting uranium from hard-to-open ores, including oxidative firing at a temperature of 500-700 ° C and sulfuric acid leaching of uranium (see Zelikman A.N. Metallurgy of rare-earth metals, thorium and uranium. M .: Metallurgizdat, 1961. 265- 268).

The disadvantages of this method are as follows:

- when roasting ore in an industrial apparatus, only partial absorption of the resulting sulfur dioxide by the ore occurs, and a significant part of it leaves the furnace with exhaust gases and requires neutralization in the gas purification system,

- the firing process is accompanied by significant entrainment of dust, mainly containing unbaked ore, which therefore must be returned to the firing.

The technical result consists in reducing the consumption of sulfuric acid for leaching cinder, reducing the consumption of reagents for neutralizing acid waste gases, the amount of waste generated and, as a result, improving the environmental situation in the processing of uranium ores, increasing the degree of extraction of uranium from the ore due to the efficient use of trapped dust.

The technical result is achieved by the fact that, in a method for extracting uranium from hard-to-open ores, including oxidative calcination at a temperature of 500-700 ° C and sulfuric acid leaching of uranium, calcined ore to a fineness of -2 or -5 mm containing sulfur and carbonates is subjected to calcination. The cinder resulting from the firing is crushed, pulp is prepared from it and used in a scrubber to neutralize the sulfur dioxide fired in the exhaust gases. The neutralized pulp is removed from the scrubber and sent to the sulfuric acid leaching of uranium.

The dust collected from the flue gases is granulated and the granules are sent for firing together with the ore.

The method is as follows. For firing, a crushed ore, for example, with a grain size of -2 or -5 mm, is fed into a tubular rotary kiln. The cinder is crushed and used to prepare pulp irrigating the first hollow scrubber of a wet gas purification system. As a result of the interaction of the carbonates contained in the ore, the sulfur dioxide contained in the exhaust gases is neutralized. As neutralization, the pulp is removed from the scrubber and sent to the leaching of uranium with sulfuric acid.

The dust trapped in the apparatuses of the dry exhaust gas treatment system of the kiln is granulated, for example, with a liquid glass solution, and the obtained granules are sent for calcination together with the initial ore.

Example. Ore with a content of 2.3% sulfur, 10-12% carbonates and 5-7% chlorites was crushed to a particle size of 100% -5 and -2 mm (the sieve composition of the samples obtained is shown in Table 1) and fired on an enlarged installation, which is a tubular rotary kiln with gas cleaning system. The extraction of uranium into solution during sulfuric acid leaching of the cinders obtained by burning the ore in the temperature range 500-700 ° C amounted to 84.8-89.6%.

Table 1 The size and sieve composition of the source ore Ore size, mm Sieve composition, mm,% -5.0 +1.6 -2.0 +1.6 -1.6 +1.0 -1.0 +0.63 -0.63 +0.4 -0.4 +0.315 -0.315 +0.16 -0.16 +0.063 -0.063 +0.05 -0.05 -5.0 46,4 - 14,4 10.1 9.1 6.6 7.5 3,7 0.7 1,5 -2.0 - 7.6 24.4 12.9 14.7 6.0 14.9 10,2 6.4 2.9

As can be seen from the results shown in table 2, as a result of firing these samples of the concentrate at a temperature of 700 ° C for 2 hours, 24.1-38.9% of sulfur in the form of dioxide passes into the exhaust gases, which necessitates its capture. Exhaust gases in this case contain up to ~ 100 g / m ³ dust and up to ~ 24 g / m ³ SO ₂ .

For trapping in a wet sulfur dioxide scrubber, a crushed cinder pulped in water was used. The test showed that in this case, the SO ₂ content decreased to 11.7 g / m ³ , i.e. by 51.2%. As a result, the total absorption of sulfur by the cinder increased by 19.9%, i.e. 1.4 times, and the consumption of sulfuric acid during cinder leaching additionally decreased by 21.0 kg / t of ore.

table 2 Sulfur distribution during ore firing Temperature - 700 ° С. 2 hours Ore size, mm PPP,% Product Pyleunos,% The yield of sulfur,% -5 3.3 Ore 4.6 one hundred Cinder 72.0 Dust 3.9 Gas 24.1 -2 3.2 Ore 12.1 one hundred Cinder 49.0 Dust 10.3 Gas 38.9

The dust carried out from the kiln practically contains more than 70% of unburnt ore and must be returned to the kiln. To do this, the dust was granulated in a drum granulator using liquid glass as a binder. The obtained granules together with crushed ore were fed for firing.

Thus, the proposed method of ore roasting provides a high degree of utilization of the sulfur contained in the ore to neutralize the acid-intensive minerals contained in it, which helps to reduce the consumption of sulfuric acid during leaching of uranium ore, reduce the amount of waste obtained during its processing and, as a result, significantly improve the environmental situation . In addition, during the oxidation of pyrite elemental gold is released, which makes it possible to extract it by known methods.

Claims (2)

1. The method of extraction of uranium from hard-to-open ores, including oxidative roasting at a temperature of 500-700 ° C and sulfuric acid leaching of uranium, characterized in that the roasting is crushed to a particle size of -2 or -5 mm ore containing sulfur and carbonates obtained by roasting the cinder is crushed, pulp is prepared from it and used in a scrubber to neutralize the sulfur dioxide fired in the exhaust gases, the neutralized pulp is removed from the scrubber and sent to uranium acid leaching of uranium. 2. The method according to claim 1, characterized in that the dust captured from the firing exhaust gases is granulated and the granules are sent for firing together with the ore.