The method of opening monazite concentrate
The invention relates to a technology developing concentrates of rare earth elements from natural phosphate concentrates. The method comprises obtaining a mixture of a mixture of monazite concentrate with soda ash, heat treatment and water processing obtained after heat treatment of the product with the release washed from phosphorus amounts of lanthanides and thorium in the form of oxides. Before preparing the charge monazite concentrate is ground to -100 mesh (-0,15 mm), the mass ratio of monazite concentrate for soda soda in the mixture upon receipt of the charge choose 1:0,5-0,65 with an excess of soda 10-40%. thermal treatment is carried out in a sealed continuous furnaces, electrically heated, water treatment is carried out at a temperature of 80-95°C and T:W=1:4. The exhaust of the reaction gases purified from eye-catching in the process of opening thoron. The technical result is the high degree of extraction (>99%) of the amount of rare earth metals and thorium in the net from phosphorus sludge in reducing the consumption of reagents (soda) and in additional commercial product of trisodium phosphate.
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Of the various methods of opening lanthanide phosphates, normal, representative of which is monazite, in practice, have found application high temperature sulfatization and alkaline intrusion sodium hydroxide solution (A. I. Mikhailichenko and other Rare earth metals. - M.: metallurgy, 1987, S. 30-37).
There is a method of opening monazite concentrate, including decomposition concentrate 96% sulfuric acid at its expense 250-300% of stoichiometry and temperature of 200 to 240° C for 2-4 hours, processing sulphate SPECA chilled water with respect to T:W=1:9-20 translated into a solution of sulphate of lanthanides, filtering solution with separation of insoluble impurities and separation of lanthanides oxalic acid at a temperature of 80° C and pH 1.5 in the form of oxalate precipitate and transfer to the hydroxide by treatment with alkali (Technology of rare and scattered elements. Ed. by K. Bolshakov A., I. 2. - M.: Higher school, 1969, S. 284-285).
The disadvantages of the method are: the frequency of the process directly from the autopsy, a large excess of reactant opening, highly aggressive process of opening monazite concentrated sulfuric acid at a great excess against stoichiometry and vysokonogaya.
Known industrial method of opening monazite concentrate by decomposition concentrate 45% sodium hydroxide solution for 3 hours at its expense 300% of stoichiometry and temperature 140° With the Department of precipitation of hydroxides of lanthanides (Technology of rare and scattered elements. Ed. by K. Bolshakov A., I. 2. - M.: Higher school, 1969, S. 289-291).
The disadvantages of this alkaline way of opening monazite concentrate are: the need for fine grinding of monazite concentrate (98% up - 360 mesh), high consumption of alkali, the duration of the periodic process - 3 hours, incomplete decomposition concentrate, highly aggressive fluids and low filterability precipitation of hydroxides.
Significant advantages compared to sulfuric acid and alkaline autopsy has high-temperature sintering rare earth concentrate with soda (A. I. Mikhailichenko, E. B. Mikhlin, Y. B. Patrikeev. Rare earth metals. - M.: metallurgy, 1987, S. 31 to 36, 41). The autopsy process monazite heat treatment with soda has been the subject of many studies. For example, “Giredmet” these studies were conducted on thermogravimetric installations, however, a detailed analysis of the process, in addition to con">The present invention is to develop a process of opening monazite concentrate heat treatment with soda to replace expensive reagents more affordable, optimum conditions for the opening temperature, the time, the replacement of periodic processes on a continuous, eliminating aggressive wastewater and reduce the amount of volatile radionuclides.
The technical result of the proposed method is to increase productivity and prevent discharge of gaseous nuclide, isotope radium - thoron.
The problem is solved by the opening of monazite soda in special sealed tubular continuous furnaces electrically heated.
The invention consists in the fact that in contrast to the known method of opening monazite concentrate, comprising obtaining a mixture of a mixture of monazite concentrate with soda ash, heat treatment charge and water treatment obtained after heat treatment of the product with the release of cleaned from impurities, including phosphorus, the amount of lanthanides and thorium in the form of oxides, in the proposed method before preparing the charge monazite conc and upon receipt of the charge choose 1:0,5-0,65 when excess 10-40% ash, thermal treatment is carried out in a sealed continuous furnaces with electric heating, and the resulting granular product is subjected to heat treatment water treated at a temperature of 80-95° C and T:W=1:4 with the subsequent use of washed from phosphorus amounts of oxides to obtain the lanthanides and thorium known methods, and the exhaust of the reaction gases are cleaned from eye-catching in the process of opening thoron.
Monazite concentrate is ground to a particle size of -100 mesh (-0,15 mm), thoroughly mixed in a mixer with soda ash (hereinafter soda), the mass ratio of monazite to the soda (M:s) equal to the level of 1:0,5-0,65, i.e. with an excess of reagent - soda at the level of 10-40%. The resulting mixture of monazite with soda is supplied to the heat treatment in a special sealed furnace continuous operation at a temperature of 820±20° C, time of heat treatment in the working zone of the furnace 30±10 minutes Obtained granular mixture through a water trap enters reulator, which due to heat product heat treatment (if necessary, heat exchanger or steam) the temperature of the pulp 80-95° C. When filling reulator pulp with a ratio of T:W=1:4 solid it is filtered. T is the oxide remains of 0.2-0.5% or less of the amount of phosphorus content in the original concentrate. From the core, i.e., the first solution by parki with subsequent crystallization is allocated trisodium phosphate. Washed from phosphorus wet oxides further processed by known methods for the extraction of lanthanide separation of thorium impurities and obtain the amount of lanthanides, which in this application will not be considered. Expected performance monazite is 170 kg/h.
The basis for the development of the proposed process was derivatographic and large-scale studies conducted on monazite number of fields. Based on these works of refined parameters of the heat treatment, a sufficient grade of milling monazite, the composition of the charge, consisting of monazite and soda ash, the kinetics of the process of heat treatment, the yield of the reaction gases, the method of determining the optimal composition of the charge, the performance of tubular sealed continuously operating furnace.
The main difference of the proposed method are: the degree of crushing monazite concentrate to -100 mesh (-0,15 mm), the mass ratio of monazite to the soda M : s level 1:0,5-0,65, i.e. with an excess of reagent-soda at 25±15% vs. stoichiometry.
The difference between the claimed process is also the I quantity of generated gaseous products, equal to the stoichiometry of the reaction:
what is within 9-12 g· EQ. of carbon dioxide per kilogram of commodity monazite, or 4.5-6 g· mol CO2or 133,6 nl/kg or 100 -133,6 nm3/t monazite concentrate. Due to the low volume of the reaction gases formed during heat treatment of monazite in sealed furnaces, they are sent to a special expansion chamber, scrubber where they are within ten half-life of thoron, washed and freed from its child elements number of thoron, neutralized more than 99.9% are to be reset.
The difference process is also low activity of wash water to separate phosphorus, level 1· 10-9CI/l, and trademarks of trisodium phosphate.
Party trademarks of monazite are working sample, which is ground to a particle size of -100 mesh. Derivatographic, or heat treatment in a laboratory environment, specify the optimum weight ratio of monazite to the soda (M:s). The optimum ratio may be 1:0.5 to 1:0,65.
According to the obtained results the relationship M:crushed monazite thoroughly mixed in a mixer with soda residence time of the charge in the working area of 30±10 minutes. The expected performance of the process on specialized industrial continuous furnaces and 170 kg/hour charge. After heat treatment of bulk charge through the water gate is continuously supplied to repulper. When reaching into reulatory density pulp T:W=1:4 solid slurry is filtered, the solid repulping in the washing solution with T:W=1:1.5, and then in water at T:W=1:0,5. In laundered so wet oxides remains of 0.2-0.5% of the amount of phosphorus contained in the monazite concentrate.
From the core, i.e., the first leaching solution through parki with subsequent crystallization allocate trisodium phosphate.
Washed from phosphorus wet oxides further processed by known methods for the extraction of lanthanide separation of thorium impurities, separating and receiving the amount of lanthanides and individual lanthanides, which in this application will not be considered.
The performance of other types of sealed furnaces, for example, with an inclined retort and heat treatment time are specified.
In the sintering process, which is described by equations (1, 2), gaseous reaction product is carbon dioxide, the amount of which is the or 100-133,6 nm3/t trademark monazite. Such a small volume of gases evolved during the reaction, that is, when the heat treatment of monazite with soda on the proposed method effectively allows them to clear of possible aerosol by known methods of gas purification, and by creating the so-called settling chamber for forming gases with time of sludge equal to ten half-life of thoron, equal in this case ~10 min, to ensure almost complete collapse, because its concentration in the exhaust gases is reduced by three orders of magnitude. The resulting solid radionuclides trapped in irrigated scrubber.
Received in a sealed furnace product heat treatment remains loose, almost does not contain the oxidized amount of the lanthanides.
When continuous discharge of the hot product of the heat treatment is leaching at 80-95° with the transfer of phosphorus in solution in the form of trisodium phosphate.
To prevent, reduce oxidation of cerium oxide oxygen to the tetravalent state, the process of cleaning should not be carried out with the stops (shift, day, and so on) for a long period.
The choice of the optimal mass ratio M:is important is heat-treated in a rotary retort furnace,
- ensure minimum energy consumption in the heat treatment of the charge,
- ensure the minimum content of soda in the wash water when washing the product of the heat treatment from trisodium phosphate, which will allow the method of parki be obtained from the wash water crystalline trisodium phosphate with minimal content PA2CO3·10H2O.
Analyses of trisodium phosphate, obtained from the research on activity, showed that he can be considered as accompanying the product, because the activity of phosphate-soda solution was 1· 10-9Ku/l total activity, and directly crystalline trisodium phosphate had an activity of the same order.
Thus, in the methods of dissection and processing of monazite, developed on a laboratory scale, novelty items are the following:
1. Use for opening trademarks of monazite concentrates continuously existing tubular, sealed electric furnaces, which leads to a sharp reduction in the volume of the gases is reduced to the volume of the reaction gases formed by the interaction of phosphates lanthanides, thorium and other metals with sodium carbonate.
2. Preotwreatmenia elemental chlorine in the case of the operation of dissolution washed from phosphorus product heat treatment in concentrated hydrochloric acid.
3. Stabilization parameters such as sintering time, temperature, capacity, weight dissection, reduction of power consumption.
4. Reducing the fineness of grind, improve the technological properties of the mixture. Derivatographic and technological study of the influence of fineness of grinding has shown that high levels of opening, not less than 99%, is achieved when grinding monazite to -100 mesh (particle size -0,15 mm).
5. Heat treatment of monazite with an optimal blend of monazite with soda M:S
6. The optimal composition of the charge to prevent excessive amounts of soda ash, without compromising the optimal parameters for the time and temperature of the heat treatment process, allows to increase the productivity of the furnace, to reduce energy consumption at the opening of monazite and get in the process of washing the product of the heat treatment with water solutions, and trisodium phosphate, with a minimum amount of soda. Extraction of trisodium phosphate from washing solutions also increases.
7. Prevention of discharge of gaseous nuclide, isotope radium - thoron, with a half-life of 54 seconds.
If the expected performance specification the article 0,765-1.02 kg· mol or 17,03-22,7 nm3per hour of carbon dioxide.
To ensure exposure of the produced gas, for example, in a hollow vessel or in irrigated scrubber, within ten half-life of thoron, to almost complete disintegration of the required amount of settling tank or scrubber is equal to the minimum ten-volume of the reaction gases. When the temperature of the hot reaction gases 100-200° With it will be 5-6,5 m3for specified performance for the charge ~170 kg/h. Scrubber wash water, caught the radionuclides in the decay of thoron, after 5 days, the disintegration of the child elements of thoron will have a slight level of activity.
The method of opening monazite concentrate, comprising obtaining a mixture of a mixture of monazite concentrate with soda ash, heat treatment charge and water treatment obtained after heat treatment of the product with the release washed from phosphorus amounts of lanthanides and thorium in the form of oxides with subsequent use of lanthanides and thorium, characterized in that before preparing the charge monazite concentrate is ground to -100 mesh (-0,15 mm), the mass ratio of monazite concentration is abotu carried out in a sealed continuous furnaces, electrically heated, water treatment is carried out at a temperature of 80-95°C and T:W=1:4, and the exhaust of the reaction gases purified from eye-catching in the process of opening thoron.