RU2729573C1 - Method of producing carbonates of rare-earth elements - Google Patents

Abstract

FIELD: metallurgy.SUBSTANCE: invention relates to hydrometallurgy of rare-earth elements (REE), in particular to a method of producing neodymium carbonate, used in production of neodymium metal and neodymium oxide for various regions: production of catalysts, electronic ceramics, pigment in glass production, etc. Method involves deposition of neodymium carbonate from an initial solution of neodymium nitrate, filtration of the residue and its drying. Initial solution containing 40 to 263 g/l of NdOand 4 to 30 g/l of HNOis fed into 20 % solution of a salt of carbonic acid – ammonium carbonate (NH)COor ammonium bicarbonate NHHCOunder isothermal conditions 39–44 °C at pulp mixing speed of 200–1,100 rpm. Excess carbonic acid salt is not less than 35 % of the stoichiometrically required amount. When using ammonium carbonate, the initial solution is fed at a rate of not more than 1.3 kg of NdO/(kg (NH)COh), and when using ammonium bicarbonate, the initial solution is fed at a rate of not more than 0.8 kg of NdO/(kg NHHCO·h).EFFECT: method achieves acceptable for the production of specific velocity filtering carbonate neodymium slurry – at least 1 m/(mh) without pre-adjustment of acidity and concentration of NdOstarting nitrate solution of neodymium, and also decrease the volume of waste water in 1½–2 times.1 cl, 1 tbl

Description

The invention relates to the hydrometallurgy of rare earth elements (REE), in particular to methods for producing carbonates of individual rare earth elements - neodymium carbonate used in the production of neodymium metal and neodymium oxide for various fields: production of catalysts, electronic ceramics, pigment in glass production, etc.

The modes of precipitation of REE carbonates significantly affect the characteristics and technological properties of sediments, including the specific rate of the subsequent filtration process. However, the published data are rather contradictory. In addition, the deposition of rare earth carbonates from chloride solutions is mainly considered (Komissarova L.N., Shatskiy V.M., Pushkina G.Ya. and others. Compounds of rare earth elements. Carbonates, oxalates, nitrates, titanates. - M .: Nauka , 1984 .-- 235 p.).

A known method of precipitation of carbonates of REE cerium group (Shtutsa MG, Kardapolov AV, Filippov VB, Sysina NA Study of the process of precipitation of carbonates of REE // Izvestiya Tomsk Polytechnic University, 2003. T.306. No. 5. Technical sciences. P.71-74), providing a filtration rate of the precipitate at the level of 1.1-2.3 m ³ / (m ² h), including the precipitation of carbonates by the simultaneous introduction of solutions of rare-earth chlorides with a concentration of 70 g / l of REE ₂ О ₃ , pH = 1.00 ... 1.26 and sodium carbonate with a concentration of 70 g / l into a buffer solution of sodium chloride (50 g / l NaCl) at a rate of 150-300 ml / min, a temperature of 45 ° C and subsequent agitation pulp for 1.5-4 hours and exposure under a layer of mother liquor for 22 hours.

The disadvantages of this method are: the long duration of the process, the formation of a significant amount of salt waste, the need for additional washing of the sediment from sodium ions, applicability to solutions with a concentration of REE ₂ O ₃ 70 g / l.

Closest to the claimed method is a method for producing rare earth carbonates, in particular cerium and lanthanum (RF Patent 2693176) providing a filtration rate of precipitates of cerium and lanthanum carbonates at the level of 1.05-1.20 and 1.20-1.45 m ³ / ( m ^2. h), respectively, comprising the precipitation of carbonates from solutions of lanthanum nitrate and cerium at a concentration of 60-70 g / l REM ₂ O ₃ and 10-45 g / l of HNO ₃ at a temperature of 20-45 ° C a solution of carbonic acid salt (180-200 g / l) in three stages. At the first stage, a solution of a salt of carbonic acid is fed until the pH of the pulp of carbonates of rare earths is in the range 4.1-5.5; in the second stage, the pulp pH is adjusted in the range of 3.7-4.5 by feeding a solution of a lanthanum or cerium salt; at the third stage, the pulp pH is set in the range of 6.5-7.0 by feeding a solution of a carbonic acid salt. The duration of each stage is 20-30 minutes. Mixing speed 800-900 rpm. At the end of the precipitation, the carbonate pulp is kept without stirring under a layer of mother liquor for 20-30 minutes to ripen (recrystallize) the sediment. This method is based on a set of initial features: the use of nitric acid solutions; stirring intensity when mixing reagents; filtration rate of precipitation is taken as a prototype.

Disadvantages of the method: the duration of the process is about 2 hours; the need to control and fine-tune the pH of the pulp during the entire process; applicability to solutions diluted up to 60-70 g / l in REE ₂ O ₃ , which increases the volume of waste water.

The technical result of the proposed invention is to achieve an acceptable for production specific filtration rate of neodymium carbonate pulp - not less than 1 m ³ / (m ² h) without preliminary adjustment of the acidity and concentration of Nd ₂ O _{3 of the} initial neodymium nitrate solution.

The technical result of the proposed method is achieved due to the fact that the method for producing neodymium carbonate includes precipitation of neodymium carbonate from a neodymium nitrate solution, filtering the precipitate and drying, characterized in that during precipitation, the initial neodymium solution with a concentration of 40-263 g / l Nd ₂ O ₃ and 4-30 g / l HNO _{3 is} fed into a 20% carbonic acid salt solution at a rate of no more than 1.3 kg Nd ₂ O ₃ / (kg (NH ₄ ) ₂ CO ₃ ^⋅ h) and no more than 0.8 kg Nd ₂ O ₃ / (kg NH ₄ HCO ^_3. h) under isothermal conditions at 39-44 ° C stirring speed pulp 200-1100 r / min, an excess of a carbonate salt at least 35% of the stoichiometrically necessary amount (RNC).

The calculation of the excess (Q) of the precipitant - carbonic acid salt (in% of CHK) is carried out according to the formula (1):

where V _oc is the volume of the precipitant solution, l;

ρ is the density of the precipitant solution, g / cm ³ ;

- концентрация соли угольной кислоты в растворе осадителе, %;

- concentration of carbonic acid salt in precipitator solution,%;

A _i and B _i is the stoichiometrically required amount of carbonic acid salt for precipitation of neodymium carbonate and neutralization of nitric acid, respectively, kg.

To precipitate neodymium carbonate with ammonium carbonate ((NH ₄ ) ₂ CO ₃ ) from neodymium nitrate solution A _i and B _i are:

and for precipitation with ammonium bicarbonate NH ₄ HCO ₃

,

- концентрации Nd₂O₃ и HNO₃ в растворе нитрата неодима, г/л;Where

,

- concentration of Nd ₂ O ₃ and HNO ₃ in neodymium nitrate solution, g / l;

- объем раствора нитрата неодима, л;

- volume of neodymium nitrate solution, l;

96; 336; 63; 79 - molecular weights (NH ₄ ) ₂ CO ₃ , Nd ₂ O ₃ , HNO ₃ and NH ₄ HCO ₃ , respectively, g / mol;

3 and 2 - stoichiometric consumption of (NH ₄ ) ₂ CO ₃ per 1 mol of Nd ₂ O ₃ during the precipitation of neodymium carbonate and HNO ₃ per 1 mol of (NH ₄ ) ₂ CO _{3 of} the acid neutralization reaction, respectively, mol;

6 - stoichiometric consumption of NH ₄ HCO ₃ per 1 mol of Nd ₂ O ₃ during the precipitation of neodymium carbonate, mol;

1000 - coefficient.

The feed rate of the component in the system Nd (NO ₃ ) ₃ solution - precipitant solution (in kg Nd ₂ O ₃ / (kg of precipitant ^, h)) is carried out according to the formula (2):

1/24 - empirical coefficient, l ^-1 ;

- масса Nd₂O₃ в растворе нитрата неодима объемом

, кг;

- the mass of Nd ₂ O ₃ in a solution of neodymium nitrate with a volume

, kg;

M _oc = A _i (1 + Q / 100 + B _i is the mass of the precipitant - carbonic acid salt, kg;

τ is the duration of deposition, h.

The data are shown in the table.

The proposed solution allows filtering with a specific rate that is an order of magnitude higher compared to the prototype. When using carbonic acid salt solution - Ammonium carbonate prototype achieved a specific filtration rate 0,37-0,73 m ³ / (m ² h) and the proposed - 1,57-4,43 m ³ / (m ^2. h). When using a solution of ammonium bicarbonate according to the prototype, the specific filtration rate is 0.47-0.65 m ³ / (m ^2. h), and according to the proposed one - 1.18-3.93 m ³ / (m ^2. h).

The volume of wastewater in the claimed method is reduced by 1.5-2 times, and the productivity of neodymium carbonate increases by 2-5 times due to the use of more concentrated initial solutions for Nd ₂ O ₃ 100-263 g / l.

While the present invention has been described in detail above, it will be apparent to those skilled in the art that changes and equivalent substitutions can be made, and such changes and substitutions are within the scope of the present invention as defined by the appended claims.

Claims (1)

A method for producing neodymium carbonate, including the precipitation of neodymium carbonate from an initial neodymium nitrate solution, filtering the precipitate and drying it, characterized in that the initial solution containing from 40 to 263 g / l Nd ₂ O ₃ and 4-30 g / l HNO ₃ , served in a 20% solution of a carbonic acid salt - ammonium carbonate (NH ₄ ) ₂ CO ₃ or ammonium bicarbonate NH ₄ HCO ₃ under isothermal conditions 39-44 ° C at a pulp stirring speed of 200-1100 rpm, and an excess of carbon acid is at least 35% of the stoichiometrically required amount, while when using ammonium carbonate, the initial solution is fed at a rate of not more than 1.3 kg Nd ₂ O ₃ / (kg (NH ₄ ) ₂ CO ₃ h), and when using ammonium bicarbonate, the original solution is fed at a rate of no more than 0.8 kg Nd ₂ O ₃ / (kg NH ₄ HCO ₃ · h).