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INVENTION
Russian Federation Patent RU2094511

METHOD FOR PROCESSING wolframite CONCENTRATE

METHOD FOR PROCESSING wolframite CONCENTRATE

Name of the inventor: Kaminsky YD .; Matsenko YA .; Semiheaps AV .; NI Kopylov .; Makarov EP
The name of the patentee: Kaminsky Yuri Dmitrievich
Address for correspondence:
Starting date of the patent: 1995.10.26

The invention relates to the production of refractory metals, rare metals and alloys. The inventive method for processing wolframite concentrate is carried out by heating the charge to mass ratio of the components in it: wolframite concentrate: (K, Na) nitrate: soda ratio of 1: (1,4-0,7): (0,7-0, 3) salt in a liquid bath at a temperature of 320-550 o C. The resultant alloy subjected to hydrometallurgical processing in a known manner to obtain a marketable product tungsten. Removing the tungsten in the commercial product is 95-98,5%. The invention allows to create technology that does not pollute the environment with harmful emissions, ensuring regeneration consumed in melting nitrate, reducing the temperature of the process.

DESCRIPTION OF THE INVENTION

The invention relates to ferrous metallurgy and can be used in the production of refractory metals, rare metals and alloys.

Known method [1] Processing of tungsten concentrate by fusing it with soda and silica at a temperature of 1400-1500 o C to obtain a melt immiscible layers and concentrating them in one of tungsten in the form of sodium salt. The composition of the initial charge to charge ratio of soda concentrate silica of 1.0: 0.17: 0.16.

The disadvantage of this method is the heat alloying process (1400-1500 o C) and high consumption of soda (165 of the theoretically required amount). The high temperature of the process casts doubt on the practical use of it because of the extreme aggressiveness of soda-alkaline melts at high temperatures and the need for special measures to protect the lining of the molten bath of the working unit.

Known methods [2, 3] Processing tungsten concentrate, where the charge instead of quartz used technical silicate lump (soda lime glass) as in one of these [3] before the melting administered operation thermolysis (firing without air) at 700 o C and are characterized by significant major drawback of high temperature melting during the formation during aggressive soda-alkaline melts.

Known method [4] of extracting tungsten tungsten material comprising forming and sintering the batch, which is prepared by mixing the carbonized tungsten material and \ or carbonaceous reactant and sodium or potassium nitrate salts in a weight ratio of components 1 :( 0.6-2.0) to form a first part of the charge, an oxidized tungsten material and \ or reagent containing metal oxides and ash in a weight ratio of components 1 :( 0.3-1.0).

Isolation of tungsten from other refractory metals (such as tantalum), a part of recyclable materials is carried out by transferring them to sodium-form, which is soluble in the aqueous medium of tungsten and insoluble in the case of other refractory metals (e.g., tantalum) which It allows you to extract tungsten into marketable products, and other metals in a form suitable for further processing. Translations into sodium compound of tungsten and other refractory metals is carried out using the "SHS" method (SHS), which is based on the exothermic oxidation reaction of carbon-containing components of the burden of sodium nitrate. As moderator of the reaction is a mixture of oxygen-containing feedstock, or raw material pre-oxidized with soda.

The method in its industrial implementation has several significant drawbacks, namely: high (in the range 900-1000 o C) temperature process, which leads to an increase in aggressiveness soda-alkaline melts and requires specially lined assembly precluding the possibility of erosion of the lining of its melt or burnout at local overheating of a separate section of its capacity; side reactions of decomposition of ammonium nitrate to form nitrogen oxides, and their separation into a gaseous medium; process provides irrevocable consumption of large quantities of nitrate (100-200% by weight of the concentrate); since the oxidation reactions are explosive in nature, their implementation requires the maintenance of an accurate ratio of the combustible component of the oxidant and the endothermic part of the charge.

According to the method described in [5] by sintering wolframite with sodium carbonate at t = 800-900 o C to accelerate decomposition of the mineral charge is added to the oxidant (sodium nitrate) in an amount of 1-4% by weight of the concentrate. The main disadvantages of this method are the high corrosiveness of the resulting alkaline melts at temperatures used, leading to a rapid erosion of the material of the furnace; the need to maintain a uniform temperature distribution in the furnace chamber to prevent the solidification of the melt in its particular areas; thermal decomposition of nitrate with emission in the gas phase of nitrogen oxides.

The closest technical solution to the proposed method is [6], tungsten extraction from wolframite concentrates fusion with soda and sodium chloride supplemented with nitrate as the oxidizer. The testing process was carried out in a crucible furnace and reflectivity. Charge consisting of wolframite (WO 3 content 73%), Na 2 Co 3, NaCl and NaNo 3 at a weight ratio 1 0.25 0.16 0.05 melted in a reverberatory furnace for 45 minutes at a temperature of 800 o C . extraction of tungsten into an aqueous solution of 99.6% was melt liquor containing Na 2 WO 4 and NaCl, after purification from the impurities are directed to the extraction of tungsten with conditioned obtain ammonium paratungstate.

The components of the charge (NaCl and Na 2 CO 3) form a eutectic melt with a melting onset temperature of 634 o C, thereby providing a heterogeneous flow of the exchange reaction between soda and tungstate.

The disadvantages of the method include the following: the process is a high temperature, and requires for its implementation refractory equipment of high reliability to the temperatures and aggressive soda-nitrate melt; under the conditions used (t 800 o C) inevitably takes place the process of thermal decomposition of ammonium nitrate with formation of nitrogen oxides; extraction of tungsten from the resulting liquor is associated with the extraction and sorption methods, because conventional methods can not obtain conditioning tungsten products. A significant drawback of this method is the need for disposal of chloride solutions.

The technical result achieved the present invention is to provide a technology, not polluting the environment with harmful emissions, ensuring regeneration consumed in melting nitrate, reducing the temperature of the process and the use thereof for the ordinary steel-making plants, to simplify and reduce the cost of technology.

This is achieved by the process at reduced temperature melting lead in the molten salt, which is formed during the melting of sodium nitrate mixture and \ or potassium, sodium and at a ratio of concentrate (1,4-0,7) (0,7-0,2) 1.

In carrying out the process uses sodium nitrate property and \ or form a fusible melts potassium (t mp308-310 o C) and the ability to assimilate more refractory metals salts, particularly soda ash. The process is carried out in the following main reactions (for example, NaNo 3):

As seen from the reaction equations, tungsten concentrate transfer in sodium form is due to the interaction with the original concentrate soda. This nitrate melt serves as environment for the exchange interaction with the ions of tungsten concentrate soda component. The resulting carbonate ferrous nitrate melt is oxidized and decomposed to Fe 3 O 4 and CO 2.

It is known that nitrates and nitrites pure alkali metal begin to decompose at a temperature 450 o C, and the introduction of nitrite into nitrate salt component melt of the higher melting and decomposition temperature (in particular, soda) nitrate decomposition temperature (nitrite) is shifted to higher temperatures. Therefore, in the proposed method of melting nitrates melt interact only with iron carbonate formed by oxidizing it to a trivalent state, and passing in the form of nitrites. Further expansion of the latter with the release of nitrogen oxides does not occur, and hence pollution of nitrogen oxides eliminated by this method.

The resulting heterogeneous mixture nitrate tungsten molten salt and insoluble reaction products (Fe 3 O 4, sodium salts of impurities and others.) Then subjected gidrovyschelachivaniyu by known schemes to transfer a cake of iron oxide and other insoluble components, and tungstate solution and nitrite (nitrite ) sodium. Next, tungsten is converted into a commodity form, and converted in the nitrite into nitrate, which after its release uparkoy returned to the head in the smelting process.

Experimental verification of the proposed method was carried out a series of experiments in an enlarged-scale laboratory. The method was performed as follows. The batch was prepared by mixing wolframite concentrate containing 61% WO 3 with soda and sodium nitrate, at a predetermined ratio and melted in a furnace vessel (V = 10 L) at 315-600 o C until the termination of gas evolution. The presence of the waste gases was controlled nitrogen oxides. After termination of gassing the melt discharged from the boiler to the reactor with agitator. Dissolution melt was performed for 0.5-1.0 hr. At a ratio of melt water and 1 (2.3) and a temperature of 90-95 o C. After the pulp sludge settling tank tungsten solution was decanted, the cake is filtered and washed on a nutsch -filter and stockpiled. Tungsten from tungsten oxide solution is recovered by known techniques. Extracting tungsten into solution from the concentrate, depending on the experimental conditions, it was 80-98,5% The results are shown in the table.

From these data it follows that:

  • shared with sodium nitrate in the consumption of less than 0.7 by weight of the concentrate a viscous melt, which hampers the mixture components reacting and resulting reduced degree of decomposition wolframite concentrate; with an increase in the proportion of sodium nitrate consumption by more than 1.4 weight degree of extraction of tungsten concentrate is stored at a high level, but the productivity of the process is reduced by reducing the proportion of concentrate in the charge;
  • common soda consumption less than 0.2-0.3 by weight of the concentrate leads to a reduction of tungsten recovery and the emergence of nitrogen oxides in gas emissions; increasing the share of soda consumption to more than 0.7 times the weight of the concentrate is not economically feasible;
  • temperature increase leads to a reduction in processing time, but at temperatures 600 o C observed the emergence of nitrogen oxides in the gas emissions due to the thermal decomposition of sodium nitrate; at a temperature less than 320 o C significantly increases processing time by reducing zhidkopodvizhnosti, increasing the viscosity of the molten mass and difficulty gassing;
  • replacing parts of sodium nitrate, potassium nitrate does not change the parameters of decomposition process wolframite concentrate, furthermore contributes to the low-melting salt melt.

As can be seen from these experiments, the proposed limits of the melting temperatures and ratios of components in the starting material can achieve the goal of the process, namely within the temperature range 320-550 o C and ratios of components in the starting material, wolframite concentrate sodium nitrate and \ or potassium soda is equal to 1 (1,4-0,7) (0,7-0,3). In these temperature ranges obtained maximum possibility of reaction of wolframite component concentrate with carbonate citrate enclosing the melt and the subsequent oxidation of the impurity components (Fe, Mn) in mixed oxide form (Fe 3 O 4, Mn 3 O 4) to obtain a melt tungstate and sodium nitrate (potassium), which is then converted by known hydrometallurgical processes in commercial product (WO 3) and a working material (NaNO 3). However, due to low melt temperatures without decomposition of sodium nitrate, which prevents the formation of nitrogen oxides in the waste gases and provides for this condition purity harmful components. Taken ratio of the components provide the optimum opportunity for the process of decomposition of raw materials and producing this most flowable nitrate, nitrate of soda melt.

Thus, the method has the following advantages.

1. Maintain the batch melting proposed composition and ratio limits its components at low temperature conditions of the process, which enables the use of standard low-temperature furnaces, as a melting vessel steel (ordinary grades such Art. 3) or cast iron boilers and similar units so when practicing the process does not require special equipment with a special lining working vessels or their production of special materials.

2. In the process of the method used in the range of temperatures (320-550 o C) and the ratio of mixture components (concentrate (K, Na) nitrate soda 1 (1,4-0,7) (0,7-0,3)) there is no emission of harmful gases - nitric oxide in the gas phase, which makes the process environmentally friendly.

3. In the method (K, Na) nitrate is used only as a low-melting medium to provide a thorough interaction of tungsten concentrate and sodium carbonate to yield sodium tungsten and further decomposition of the formed carbonate iron (manganese) and its oxidation to Fe 3 O 4 with a further transfer of the last in the cake. Formed during the sodium nitrite (potassium) (after completion of the translation of tungsten in commercial product) can be recycled to be used again and nitrate smelting.

4. According to the proposed method silicate component does not concentrate into solution by leaching, and the cake is concentrated in the insoluble. Therefore, the content of silicate ions in the leaching solution a little, hence eliminating the need for redistribution of additional purification of this impurity, which simplifies the process and leaching resulting in melting the melt and increases the quality of commercial product.

5. developed through the extraction of tungsten technology into marketable products is 95-98,5%

CLAIM

Method for processing wolframite concentrate comprising preparing a blend by mixing wolframite concentrate with nitrate salt of an alkali metal and ash, melting the resulting blend with subsequent hydrometallurgical treatment resulting fusion product, characterized in that the mixing is carried out using as a nitrate salt of an alkali metal sodium nitrate and / or potassium at a weight ratio of wolframite concentrate is sodium nitrate and / or potassium soda 1.4 0.7 0.7 1 0.3 respectively, and the melting is carried out in the furnace vessel at 320 550 o C until cessation of gas evolution.

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Publication date 16.03.2007gg