Method for recovering rare earth metals from solid minerals and/or by-products of solid mineral processing

Abstract

The invention relates to the technology of recovery of rare-earth elements form both solid fossil and technology-related materials obtained by means of their target-oriented processing. Rare-earth elements recovery method include the acid leaching of ground to less than 100 m solid fossil and technology-related materials with the mixture of sulphuric and nitric acid at ratio from 6:1 to 1:1 mass parts, at the concentration in mixture of acids less than 15 wt. % at liquid/solid phases ratio of L:S from 2:1 to 6:1 mass parts. During the leaching operation progress the vacuum-impulse action is conducted during all operation of transferring of rare-earth elements compounds into a solution and obtaining of a precipitate of remained solid fossil and technology-related materials. The obtained precipitate of solid fossil and technology-related materials is separated from leaching solution. Separation of rare-earth elements from leaching solution is conducted using ion-exchange filter or membrane filter.

Claims

1. A method of recovery of rare-earth elements from solid fossil and/or technology-related materials containing rare-earth elements, comprising a acid leaching of compounds of rare-earth elements from materials with a solution of mixture of sulphuric and nitric acid while stirring the leaching solution and transferring of rare-earth elements compounds into the solution and obtaining of insoluble precipitate of remaining solid material, a separation of insoluble precipitate from the leaching solution and recovery of compounds of rare-earth elements from the leaching solution, wherein prior to acid leaching a grinding of material particles is conducted to a size of less than 100 m, and the leaching operation is conducted at simultaneous vacuum-impulse action with a ratio in mixture of sulphuric and nitric acids from 6:1 to 1:1 mass parts at a concentration in mixture of acids less than 15 wt. % at liquid/solid phases ratio (L:S) from 2:1 to 6:1 mass parts.

2. Method of claim 1, wherein the rare-earth elements recovery from leaching solution is perforated by passing leaching solution through a cation-exchange filter.

3. Method of claim 1, wherein the rare-earth elements recovery from leaching solution is performed by passing leaching solution through a membrane filter.

Description

EXAMPLE 1

(1) One of the technology-related origin materialsapatite phosphogypsumwas used as a solid and technology-related material. The influence of phosphogypsum grinding on REEs leaching rate is illustrated with the examples, shown in table 1 where the samples of phosphogypsum of different dispersibility were used. sample No 1 (origin phosphogypsum)of particle size more than 100 m, obtained by screening of fine fractions from refuse tips; sample No 2of particle size less than 10-15 m, obtained by grinding of origin in rotary-pulse device; sample No 3of particle size less than 100 m, obtained by grinding of origin in dynamic activator;

(2) When processing all three samples the similar modes of REEs leaching were maintained.

(3) TABLE-US-00001 mass of samples 50 g.; total REEs content in a sample 437 mg.; ratio (mass) of sulphuric and nitric acids 3:1; concentration (mass) of acids mixture 5%; ratio (mass) of liquid and solid phases (L:S) 5:1; leaching duration at 20 C. 15 min.

(4) The leaching operation was performed with vacuum-impulse action under pressure 1 kPa.

(5) Table #1 shows the experiment results.

(6) Dependence of REEs leaching rate on phosphogypsum dispersibility.

(7) TABLE-US-00002 TABLE #1 Phosphogypsum Phosphogypsum REEs* content in Leaching sample particle size, m solution, mg rate, % No 1 (origin) more than 100 323.1 73.8 No 2 less than 10-15 416.9 95.4 No 3 less than 100 377.1 86.3 *Note: expressed as solids content.

(8) The effectiveness of REEs recovery by leaching was estimated by total REEs leaching rate.

(9) REEs content in the original sample and solution was determined by data of mass-spectral method with inductively coupled plasma.

(10) As it follows from Table #1, the REEs leaching rate from, phosphogypsum increases significantly while phosphogypsum dispersibility increasing and achieve the value of 95.4% when using particle size less than 10-15 m. As a result the REEs recovery rate from phosphogypsum increases essentially.

EXAMPLE 2

(11) Loparite concentrate grade of KL-1 is used as material. The influence of loparite concentrate grinding on REEs leaching rate is illustrated with the examples, shown in Table #2, where two samples of material of different dispersibility were used: sample #1 (original concentrate)particle size up to 75 m; sample #2particle size less than 100 m.

(12) When processing samples the similar modes of REEs leaching were maintained.

(13) TABLE-US-00003 mass of samples 50 g.; total REEs content in a sample 510 mg.; ratio (mass) of sulphuric and nitric acids 2:1; concentration (mass) of acids mixture 5%; ratio (mass) of liquid and solid phases (L:S) 4:1; leaching duration at 50 C. 30 min.

(14) The leaching operation was performed with vacuum-impulse action under the pressure of 1-2 KPa.

(15) Table #2 shows the experiment results.

(16) TABLE-US-00004 TABLE #2 Loparite concentrate Loparite concentrate REEs* content in Leaching sample particles size, m solution, mg rate, % No 1 (origin) up to 75 465.0 91.1 No 2 less than 100 370.0 72.5 *Note: expressed as solids content.

(17) Therefore, the claimed method of recovery REEs from solid fossil and technology-related materials allows increasing the REEs leaching rate not only from technology-related waste such as phosphogypsum as well as solid fossil containing REEs in parallel with the method simplification.