PROCESS FOR METALLURGY AND SEPARATING RARE EARTH CONCENTRATE USING COMBINATION METHOD

Abstract

The present invention provides a process for metallurgy and separating a rare earth concentrate using a combination method, the process including: treating the rare earth concentrate containing bastnaesite by using a method including roasting under an atmosphere, leaching with hydrochloric acids, and roasting with a sulfuric acid, wherein stepping acid leaching with low-concentration hydrochloric acids is controlled during the leaching with the hydrochloric acids so as to obtain a rare earth solution with a high concentration (150-250 g/L REO), such that a leaching rate of Ce reaches 60% or more, and the content of F.sup.− in a leaching liquor is reduced by aging; and rare earth is further recovered from a leach residue by roasting with the sulfuric acid and leaching with water, and the total yield of the rare earth reaches 95% or more.

Claims

1. A process for metallurgy and separating a rare earth concentrate using a combination method, the process comprising: (1) decomposing the rare earth concentrate by roasting under a certain roasting atmosphere to obtain a roasted concentrate; (2) adding the roasted concentrate with a hydrochloric acid to leach rare earth, and collecting a leaching liquor of rare earth and a leach residue respectively after solid-liquid separation; and (3) dehydrating the leach residue, then adding the dehydrated leach residue with a concentrated sulfuric acid, roasting, collecting a roasted product, leaching the roasted product with water, and neutralizing to remove impurities to obtain a rare earth sulfate solution.

2. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein in step (1), the roasting atmosphere during the roasting comprises one or more of water vapor, air, CO, and CO2.

3. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein in step (1), the roasting is at a roasting temperature of 350° C. to 650° C.

4. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein in step (2), the leaching with the hydrochloric acid preferably comprises two or more steps of countercurrent leaching with hydrochloric acids, wherein in the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue, and next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with the hydrochloric acid in the previous step, and next, the second-step leach residue is leached with the hydrochloric acid.

5. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein in step (2), the hydrochloric acids are added in the way that 2 to 5 stages of continuous cocurrent leaching are carried out during the leaching, and hydrochloric acids are controlled to be added in a concentration gradient during each stage of leaching to keep the acidity of a mixed solution at 0.01 mol/L to 0.6 mol/L during the leaching.

6. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein in step (2), a leaching temperature during the leaching with the hydrochloric acids is controlled to be 10° C. to 75° C.

7. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein in step (3), a mass ratio (w/w) of the concentrated sulfuric acid to the dehydrated leach residue is (0.3 to 1.2): 1.

8. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein in step (3), the roasting with the sulfuric acid is at a temperature of 200° C. to 450° C., and the leaching with water is at a temperature of 20° C. to 50° C.

9. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein step (3) further comprises: separating the obtained rare earth sulfate solution by extraction, or transforming the obtained rare earth sulfate solution by extraction or transforming the obtained rare earth sulfate solution by precipitation to obtain a rare earth chloride solution; and separating the rare earth chloride solution by extraction to obtain a single rare earth compound.

10. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein in step (2), the obtained leaching liquor of the rare earth is aged at 60° C. to 90° C. for 1 to 5 hours, and solid-liquid separation is performed to obtain a rare earth chloride solution and a rare earth fluoride powder product; and the obtained rare earth chloride solution is combined with the rare earth chloride solution obtained by transforming the rare earth sulfate solution in step (3), and separating the combined solution by extraction to obtain a single rare earth compound.

11. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1, wherein water or an alkaline liquid is sprayed onto fluorine-containing tail gas generated during the roasting in step (1) or defluorination is performed on the fluorine-containing tail gas using one or two adsorbents of a rare earth oxide and a rare earth hydrated oxide to recover a rare earth fluoride product; and sulfur-containing tail gas generated in the roasting with the sulfuric acid in step (3) is desulfurized and recycled to obtain a sulfuric acid product.

12. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 2, wherein in step (1), the roasting is at a roasting temperature of 350° C. to 650° C.

13. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 2, wherein in step (2), the leaching with the hydrochloric acid preferably comprises two or more steps of countercurrent leaching with hydrochloric acids, wherein in the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue, and next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with the hydrochloric acid in the previous step, and next, the second-step leach residue is leached with the hydrochloric acid.

14. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 3, wherein in step (2), the leaching with the hydrochloric acid preferably comprises two or more steps of countercurrent leaching with hydrochloric acids, wherein in the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue, and next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with the hydrochloric acid in the previous step, and next, the second-step leach residue is leached with the hydrochloric acid.

15. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 2, wherein in step (2), the hydrochloric acids are added in the way that 2 to 5 stages of continuous cocurrent leaching are carried out during the leaching, and hydrochloric acids are controlled to be added in a concentration gradient during each stage of leaching to keep the acidity of a mixed solution at 0.01 mol/L to 0.6 mol/L during the leaching.

16. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 3, wherein in step (2), the hydrochloric acids are added in the way that 2 to 5 stages of continuous cocurrent leaching are carried out during the leaching, and hydrochloric acids are controlled to be added in a concentration gradient during each stage of leaching to keep the acidity of a mixed solution at 0.01 mol/L to 0.6 mol/L during the leaching.

17. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 2, wherein in step (2), a leaching temperature during the leaching with the hydrochloric acids is controlled to be 10° C. to 75° C.

18. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 3, wherein in step (2), a leaching temperature during the leaching with the hydrochloric acids is controlled to be 10° C. to 75° C.

19. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 4, wherein in step (2), a leaching temperature during the leaching with the hydrochloric acids is controlled to be 10° C. to 75° C.

20. The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 5, wherein in step (2), a leaching temperature during the leaching with the hydrochloric acids is controlled to be 10° C. to 75° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] To make the content of the present invention easier to understand clearly, the present invention will be further described in detail based on the specific embodiments of the present invention and the accompanying drawings.

[0039] FIG. 1 is a flow diagram of a process for metallurgy and separating a rare earth concentrate by a combination method according to the present invention.

DETAILED DESCRIPTION

Embodiment 1

[0040] The rare earth concentrate processed by the process described in this embodiment is a bastnaesite and monazite mixed rare earth concentrate. According to the process flow diagram shown in FIG. 1, the process for metallurgy and separating the rare earth concentrate by the combination method includes the following steps.

[0041] (1) The bastnaesite and monazite mixed rare earth concentrate is roasted under an air atmosphere (the content of oxygen is 21%) at 500° C. for 4 h to obtain a roasted concentrate.

[0042] In this step, HF that escapes during the roasting is sprayed with water.

[0043] (2) The obtained roasted concentrate is added with hydrochloric acids and subjected to 4 stages of continuous cocurrent leaching at 25° C. The initial concentration of the hydrochloric acid is 6 mol/L, and the use ratio of the hydrochloric acid to the roasted concentrate is 1.0 mol of the hydrochloric acid/100 g of the rare earth concentrate. After solid-liquid separation, a leaching liquor of rare earth and a leach residue are collected respectively, and the content of the rare earth in the obtained leaching liquor of the rare earth is 238 g/L, the leaching rate of the rare earth is 77%, and the leaching rate of Ce is 70%.

[0044] In this step, the leaching with the hydrochloric acids preferably includes two or more steps of countercurrent leaching with the hydrochloric acids. In the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue. Next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with the hydrochloric acid in the previous step; and next, the second-step leach residue is leached with the hydrochloric acid.

[0045] In this step, the hydrochloric acids are added in the way that 4 stages of continuous cocurrent leaching are carried out during the leaching, the concentrations of hydrochloric acids are controlled, 1.5 mol/L, 2 mol/L, 6 mol/L and 8 mol/L of the hydrochloric acids are respectively added in 1 to 4 stages, and the acidity of a mixed solution decreases gradually between 0.1-0.05 mol/L.

[0046] In this step, the leaching liquor of the rare earth is aged at 65° C. for 4 h. Solid-liquid separation is performed to obtain a rare earth chloride solution and a rare earth fluoride precipitate. The content of F in the rare earth chloride solution is 1.9 mg/L. The rare earth fluoride precipitate is dried to obtain a rare earth fluoride product.

[0047] (3) After the obtained leach residue is washed, dried and dehydrated till the moisture content is 9%, a concentrated sulfuric acid is added and roasting is performed at 300° C. for 3 h, wherein the mass ratio (w/w) of the concentrated sulphuric acid to the leach residue is controlled to be 0.3:1.

[0048] A roasted product is collected, added with water and leached with water at 25° C. for 4 h, and after neutralization for impurity removal, a 32 g/L rare earth sulfate solution is prepared. The total yield of the rare earth is 97%. The obtained rare earth sulfate solution is transformed by extraction to obtain a rare earth chloride solution, which is combined with the rare earth chloride solution in step (2). The combined solution is separated by extraction to obtain a single rare earth compound product.

[0049] In this step, sulfur-containing waste gas generated during the roasting with the sulfuric acid is recovered by means of water washing, spraying and absorbing to obtain a sulfuric acid product.

Embodiment 2

[0050] The rare earth concentrate processed by the process described in this embodiment is a bastnaesite and monazite mixed rare earth concentrate. The process for metallurgy and separating the rare earth concentrate by the combination method includes the following steps.

[0051] (1) The bastnaesite and monazite mixed rare earth concentrate is roasted under a low oxidizing air atmosphere (the content of oxygen is controlled to be 12% by adjusting the opening degree of an air inlet valve) at 500° C. for 4 h to obtain a roasted concentrate, wherein the opening degree of the air inlet valve is 50%.

[0052] In this step, HF that escapes during the roasting is sprayed with water for recovery.

[0053] (2) The obtained roasted concentrate is added with hydrochloric acids and subjected to 4 stages of continuous cocurrent leaching at 25° C. The initial concentration of the hydrochloric acid is 6 mol/L, and the use ratio of the hydrochloric acid to the roasted concentrate is 1.0 mol of the hydrochloric acid/100 g of the rare earth concentrate. After solid-liquid separation, a leaching liquor of rare earth and a leach residue are collected respectively, and the content of the rare earth in the obtained leaching liquor of the rare earth is 250 g/L, the leaching rate of the rare earth is 80%, and the leaching rate of Ce is 75%.

[0054] In this step, the leaching with the hydrochloric acids preferably includes two or more steps of countercurrent leaching with the hydrochloric acids. In the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue. Next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with hydrochloric acid in the previous step; and next, the second-step leach residue is leached with the hydrochloric acid.

[0055] In this step, the hydrochloric acids are added in the way that 4 stages of continuous cocurrent leaching are carried out during the leaching, the concentrations of the hydrochloric acids are controlled, 1.5 mol/L, 2 mol/L, 6 mol/L and 8 mol/L of the hydrochloric acids are respectively added in 1 to 4 stages, and the acidity of a mixed solution decreases gradually between 0.1-0.05 mol/L.

[0056] In this step, the leaching liquor of the rare earth is aged at 80° C. for 4 h. Solid-liquid separation is performed to obtain a rare earth chloride solution and a rare earth fluoride precipitate. The content of F in the rare earth chloride solution is 1.2 mg/L. The rare earth fluoride precipitate is dried to obtain a rare earth fluoride product.

[0057] (3) After the obtained leach residue is washed, dried and dehydrated till the moisture content is 9%, the concentrated sulfuric acid is added and roasting is performed at 300° C. for 3 hours, wherein the mass ratio (w/w) of the concentrated sulphuric acid to the leach residue is controlled to be 0.3:1.

[0058] A roasted product is collected, added with water and leached with water at 25° C. for 4 h, and after neutralization for impurity removal, a 32 g/L rare earth sulfate solution is prepared. The total yield of the rare earth is 97%. The obtained rare earth sulfate solution is transformed by extraction to obtain a rare earth chloride solution, which is combined with the rare earth chloride solution in step (2). The combined solution is separated by extraction to obtain a single rare earth compound product.

[0059] In this step, sulfur-containing waste gas generated during the roasting with the sulfuric acid is recovered by means of water washing, spraying and absorbing to obtain a sulfuric acid product.

Embodiment 3

[0060] The rare earth concentrate processed by the process described in this embodiment is a bastnaesite and monazite mixed rare earth concentrate. The process for metallurgy and separating the rare earth concentrate by the combination method includes the following steps.

[0061] (1) The bastnaesite and monazite mixed rare earth concentrate is roasted under a water vapor atmosphere at 650° C. for 4 h to obtain a roasted concentrate, wherein the opening degree of an air inlet valve is 100%.

[0062] In this step, HF that escapes during the roasting is recovered by a rare earth oxide adsorbent to obtain a rare earth fluoride product.

[0063] (2) The obtained roasted concentrate is added with hydrochloric acids and subjected to 4 stages of continuous co-current leaching at 25° C. The initial concentration of the hydrochloric acid is 6 mol/L, and the use ratio of hydrochloric acid to the roasted concentrate is 1.0 mol of hydrochloric acid/100 g of the rare earth concentrate. After solid-liquid separation, a leaching liquor of rare earth and leach residue are collected respectively, and the content of rare earth in the obtained leaching liquor of rare earth is 235 g/L, the leaching rate of rare earth is 75%, and the leaching rate of Ce is 69%.

[0064] In this step, the leaching with the hydrochloric acids preferably includes two or more steps of countercurrent leaching with the hydrochloric acids. In the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue. Next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with the hydrochloric acid in the previous step; and next, the second-step leach residue is leached with the hydrochloric acid.

[0065] In this step, the hydrochloric acids are added in the way that 4 stages of continuous cocurrent leaching are carried out during the leaching, the concentration of the hydrochloric acid is controlled, 1.5 mol/L, 2 mol/L, 6 mol/L and 8 mol/L of the hydrochloric acids are respectively added in 1 to 4 stages, and the acidity of a mixed solution decreases gradually between 0.1-0.05 mol/L.

[0066] In this step, the leaching liquor of the rare earth is aged at 80° C. for 4 h. Solid-liquid separation is performed to obtain a rare earth chloride solution and a rare earth fluoride precipitate. The content of F in the rare earth chloride solution is 1.5 mg/L. The rare earth fluoride precipitate is dried to obtain a rare earth fluoride product.

[0067] (3) After the obtained leach residue is washed, dried and dehydrated till the moisture content is 9%, the concentrated sulfuric acid is added and roasting is performed at 300° C. for 3 hours, wherein the mass ratio (w/w) of the concentrated sulphuric acid to the leach residue is controlled to be 0.3:1.

[0068] A roasted product is collected, added with water and leached with water at 25° C. for 4 hours, and after neutralization for impurity removal, a 32 g/L rare earth sulfate solution is prepared. The total yield of the rare earth is 95%. The obtained rare earth sulfate solution is transformed by extraction to obtain a rare earth chloride solution, which is combined with the rare earth chloride solution in step (2). The combined solution is separated by extraction to obtain a single rare earth compound product.

[0069] In this step, sulfur-containing waste gas generated during the roasting with the sulfuric acid is recovered by means of water washing, spraying and absorbing to obtain a sulfuric acid product.

[0070] The steps of Embodiments 4 to 23 are as shown in Embodiments 1 to 3. The conditions of each step are as shown in Tables 2 to 4 below. The final total yields of rare earth are as shown in Table 4.

TABLE-US-00002 TABLE 2 Step 1 Treatment of Serial Roasting Roasting fluorine- number of Type of temperature time containing embodiment mineral Atmosphere ° C. h tail gas Embodiment 4 Bastnaesite Low oxidizing air 400 4 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 5 Bastnaesite Low oxidizing air 500 0.5 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 6 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 7 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 8 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 9 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 18%) Embodiment 10 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 8%) Embodiment 11 Bastnaesite Low oxidizing air 500 2 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 12 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 13 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 14 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 15 Bastnaesite Low oxidizing air 500 4 Water spray and monazite atmosphere (oxygen content 12%) Embodiment 16 Bastnaesite Water vapor and 450 3 Adsorption with air mixed gas a rare earth dehydrated oxide Embodiment 17 Mixed rare Water vapor and CO 600 4 Adsorption with earth mixed gas a rare earth concentrate oxide in Baotou Embodiment 18 Mixed rare Low oxidizing air 650 3 Spraying with earth atmosphere (oxygen liquid alkali concentrate content 12%) in Baotou Embodiment 19 Bastnaesite Air and CO.sub.2 mixed 350 4 Water spray and xenotime gas Embodiment 20 Bastnaesite, Water vapor and N.sub.2 500 6 Adsorption with monazite and mixed gas a rare earth xenotime dehydrated oxide Embodiment 21 Bastnaesite Water vapor and CO.sub.2 400 3 Adsorption with and monazite mixed gas a rare earth oxide Embodiment 22 Bastnaesite Water vapor and air 500 3 Adsorption with and apatite mixed gas rare earth dehydrated oxide Embodiment 23 Bastnaesite CO and CO.sub.2 mixed gas 450 4 Water spray

TABLE-US-00003 TABLE 3 Step 2 Acid-ore ratio Content mol of rare Number of Concentration hydrochloric earth in Leaching stage for Serial One or more Leaching of hydrochloric acid/100 g leaching rate of Leaching continuous number of Type of steps of temperature acid rare earth liquor rare earth rate of Ce cocurrent embodiment mineral leaching ° C. mol/L concentrate g/L % % leaching Embodiment 4 Bastnaesite Yes 25 6 1.0 210 72 71 4 and monazite Embodiment 5 Bastnaesite Yes 25 6 1.0 190 71 62 4 and monazite Embodiment 6 Bastnaesite No 25 6 1.0 218 74 69 4 and monazite Embodiment 7 Bastnaesite Yes 40 6 1.0 215 72 62 4 and monazite Embodiment 8 Bastnaesite Yes 25 6 1.0 202 75 61 4 and monazite Embodiment 9 Bastnaesite Yes 25 6 1.0 243 78 73 4 and monazite Embodiment 10 Bastnaesite Yes 25 6 1.0 250 81 76 4 and monazite Embodiment 11 Bastnaesite Yes 25 6 1.0 230 75 69 4 and monazite Embodiment 12 Bastnaesite Yes 65 6 1.0 195 70 60 4 and monazite Embodiment 13 Bastnaesite Yes 25 6 1.0 250 77 68 4 and monazite Embodiment 14 Bastnaesite Yes 25 6 1.0 250 80 75 4 and monazite Embodiment 15 Bastnaesite Yes 25 6 1.0 250 80 75 4 and monazite Embodiment 16 Bastnaesite No 25 3.5 0.7 186 90 89 3 Embodiment 17 Mixed rare Yes 10 4 1.5 150 70 60 5 earth concentrate in Baotou Embodiment 18 Mixed rare Yes 20 10 1.2 170 71 62 4 earth concentrate in Baotou Embodiment 19 Bastnaesite No 30 7 2.0 195 75 73 3 and xenotime Embodiment 20 Bastnaesite, Yes 55 5 0.4 180 70 65 3 monazite and xenotime Embodiment 21 Bastnaesite Yes 40 4 0.9 245 76 69 4 and monazite Embodiment 22 Bastnaesite No 75 4 0.9 199 65 60 3 and apatite Embodiment 23 Bastnaesite No 25 3 1.9 152 95 95 2 Step 2 First Second Third Fourth Fifth Content stage of stage of stage of stage of stage of Maintaining of F in Serial acidity acidity acidity acidity acidity acidity of Aging Aging rare earth number of increase increase increase increase increase mixed liquid temperature time chloride embodiment mol/L mol/L mol/L mol/L mol/L mol/L ° C. h mg/L Embodiment 4 1.5 2 6 8 0.1-0.05 80 4 1.4 Embodiment 5 1.5 2 6 8 0.1-0.05 80 4 1.5 Embodiment 6 1.5 2 6 8 0.1-0.05 80 4 1.2 Embodiment 7 1.5 2 6 8 0.1-0.05 80 4 2 Embodiment 8 1.5 2 6 8 0.3-0.2  80 4 1.8 Embodiment 9 1.5 2 6 8 0.1-0.05 80 4 1.5 Embodiment 10 1.5 2 6 8 0.1-0.05 80 4 1.2 Embodiment 11 1.5 2 6 8 0.1-0.05 80 4 1.4 Embodiment 12 1.5 2 6 8 0.1-0.05 80 4 2.5 Embodiment 13 1.5 2 6 8 0.2-0.1  80 4 1.6 Embodiment 14 1.5 2 6 8 0.1-0.05 80 2 2.2 Embodiment 15 1.5 2 6 8 0.1-0.05 80 4 1.2 Embodiment 16 2 4 6 0.1-0.05 65 3 2.3 Embodiment 17 1.6 2.2 4.2 5.8 7.5 0.6-0.5  60 2 4.5 Embodiment 18 2 3 4 6 0.4-0.3  90 3 1.5 Embodiment 19 2 4 7 0.6-0.55 80 3 1.1 Embodiment 20 3 5 8 0.1-0.02 70 1 7.5 Embodiment 21 3 4 6 8 0.2-0.1  70 5 1.5 Embodiment 22 2 5 7 0.15-0.05  90 3 5.6 Embodiment 23 3 5 0.1-0.05 80 2 2.3

TABLE-US-00004 TABLE 4 Step 3 Moisture Concentration content of Temperature Time for of rare Total Serial dehydrated Roasting Roasting Acid-ore for leaching leaching earth sulfate yield of number of Type of leach residue temperature time ratio with water with water solution rare earth embodiment mineral % ° C. h w/w ° C. h g/L % Embodiment 4 Bastnaesite 9 300 3 0.5:1 25 4 30 95 and monazite Embodiment 5 Bastnaesite 9 230 4 0.4:1 28 5 25 90 and monazite Embodiment 6 Bastnaesite 9 300 3 0.4:1 25 4 32 94 and monazite Embodiment 7 Bastnaesite 8 250 3 0.5:1 30 4 30 95 and monazite Embodiment 8 Bastnaesite 8 300 4 0.6:1 25 4 27 95 and monazite Embodiment 9 Bastnaesite 9 300 3 0.3:1 25 4 32 97 and monazite Embodiment 10 Bastnaesite 9 300 3 0.3:1 25 4 32 98 and monazite Embodiment 11 Bastnaesite 9 300 3 0.4:1 25 4 30 95 and monazite Embodiment 12 Bastnaesite 8 250 3 0.5:1 30 4 29 94 and monazite Embodiment 13 Bastnaesite 9 300 3 0.3:1 25 4 31 96 and monazite Embodiment 14 Bastnaesite 9 300 3 0.3:1 25 4 32 97 and monazite Embodiment 15 Bastnaesite 9 300 3 0.3:1 40 4 28 92 and monazite Embodiment 16 Bastnaesite 9 200 4 0.4:1 35 3 26 94 Embodiment 17 Mixed rare 8 350 3 1.2:1 40 2 28 92 earth concentrate in Baotou Embodiment 18 Mixed rare 9 450 1 0.5:1 50 3 45 96 earth concentrate in Baotou Embodiment 19 Bastnaesite 9 300 4 0.3:1 40 4 31 96 and xenotime Embodiment 20 Bastnaesite, 8 400 3 0.4:1 32 3 30 95 monazite and xenotime Embodiment 21 Bastnaesite 10 350 2 0.4:1 35 4 31 97 and monazite Embodiment 22 Bastnaesite 9 400 3 0.8:1 20 3 33 95 and apatite Embodiment 23 Bastnaesite 8 400 4 0.5:1 38 3 32 96

[0071] It thus can be seen that a variety of complex rare earth minerals can be comprehensively processed through the process provided by the present invention, and the whole process has a wider industrial applicability. Most fluorine is converted into HF gas to enter tail gas by roasting under the atmosphere, and the fluorine-containing product is prepared by means of adsorption and recovery. Through multiple stages of continuous leaching with the hydrochloric acids and adjustment and control of the acidity, a high-concentration rare earth chloride solution (150-250 g/L REO) is obtained. Meanwhile, the leaching rate of the rare earth reaches more than 70%. The content of F.sup.− in the leaching liquor is reduced by aging, and the rare earth fluoride product is obtained to prevent fluorine from entering the leach residue. Thus, the problem that the fluorine-containing and sulfur-containing mixed tail gas during the roasting with a sulfuric acid is difficult to process is solved. Rare earth in the leach residue is further recovered by roasting with the sulfuric acid and leaching with water, and the total yield of the rare earth reaches more than 95%. Environmentally friendly, efficient and clean production of such mineral-type rare earth concentrates is realized.

[0072] Obviously, the foregoing embodiments are merely examples for clear description, and are not limitations to the implementations. For those of ordinary skill in the art, other different forms of changes or modifications may be made based on the above description. There is no need and it is also impossible to list all the implementations herein. All obvious changes or variations derived therefrom are still within the scope of protection of the present invention.