Mineralizer Composition and Pidgeon Silicothermic Process for Smelting Magnesium

Abstract

A mineralizer composition for Pidgeon silicothermic process for smelting magnesium consists of fluorite and a boron-containing compound. Amounts of the fluorite and the boron-containing compound meet the following equation:

M.sub.fluo-original=(1−x)M.sub.fluo+(m)(x)M.sub.B,

where, M.sub.fluo-original is a mass of the fluorite required in a conventional Pidgeon silicothermic process in which no boron-containing compound is introduced to replace a fraction or all of the total fluorite, M.sub.fluo is a mass of the fluorite in the composition, M.sub.B is a mass of the boron-containing compound in the composition, 0.5≤x≤1, and 2≤m≤8. A Pidgeon silicothermic process for smelting magnesium is also provided, which employs the mineralizer composition. The composition and process of the disclosure enable reduction and even avoidance of dust pollution caused by fluorite-containing magnesium slag.

Claims

1. A mineralizer composition for Pidgeon silicothermic process for smelting magnesium, consisting of fluorite and a boron-containing compound; wherein amounts of the fluorite and the boron-containing compound meet the following equation:
M.sub.fluo-original=(1−x)M.sub.fluo+(m)(x)M.sub.B, and wherein, M.sub.fluo-original is a mass of the fluorite required in a conventional Pidgeon silicothermic process in which no boron-containing compound is introduced to replace a fraction or all of the total fluorite, M.sub.fluo is a mass of the fluorite in the composition, M.sub.B is a mass of the boron-containing compound in the composition, 0.5≤x≤1, and 2≤m≤8.

2. The composition according to claim 1, wherein 0.5≤x<1.

3. The composition according to claim 2, wherein 0.5<x<1.

4. The composition according to claim 1, wherein 4≤m≤8.

5. The composition according to claim 1, wherein the boron-containing compound is selected from a group consisting of boric acid, borate, boric anhydride, lithium metaborate, sodium metaborate, sodium tetraborate, potassium metaborate, magnesium metaborate, calcium metaborate, barium metaborate, lead borate, disodium octaborate tetrahydrate and a combination thereof.

6. The composition according to claim 5, wherein the boron-containing compound is boric acid or borate in powder form.

7. A Pidgeon silicothermic process for smelting magnesium, comprising providing a mineralizer composition, the composition consisting of fluorite and a boron-containing compound; wherein amounts of the fluorite and the boron-containing compound meet the following equation:
M.sub.fluo-original=(1−x)M.sub.fluo+(m)(x)M.sub.B, and wherein, M.sub.fluo-original is a mass of the fluorite required in a conventional Pidgeon silicothermic process in which no boron-containing compound is introduced to replace a fraction or all of the total fluorite, M.sub.fluo is a mass of the fluorite in the composition, M.sub.B is a mass of the boron-containing compound in the composition, 0.5≤x≤1, and 2≤m≤8.

8. The process according to claim 7, wherein 0.5≤x<1.

9. The process according to claim 8, wherein 0.5<x<1.

10. The process according to claim 7, wherein 4≤m≤8.

11. The process according to claim 7, wherein the boron-containing compound is selected from a group consisting of boric acid, borate, boric anhydride, lithium metaborate, sodium metaborate, sodium tetraborate, potassium metaborate, magnesium metaborate, calcium metaborate, barium metaborate, lead borate, disodium octaborate tetrahydrate and a combination thereof.

12. The process according to claim 11, wherein the boron-containing compound is boric acid or borate in powder form.

13. The process according to claim 7, wherein the boron-containing compound is contained in a magnesium slag produced by the process in an amount of 0.2 to 1.5 wt %, preferably 0.3 to 0.5 wt %.

14. A Pidgeon silicothermic process for smelting magnesium, comprising: grinding and mixing calcined dolomite, ferrosilicon as a reducing agent, and a mineralizer composition according to claim 1; briquetting the mixture so obtained; placing the briquettes so obtained into a reduction retort followed by heating the briquettes to a temperature of 1120 to 1200° C. and evacuating the retort to 10 to 20 Pa; subjecting the briquettes to said temperature for 6 to 10 h; and collecting raw magnesium after cooling; wherein, the briquette comprises 12-18 wt % of the ferrosilicon, 0.2-3.5 wt % of the mineralizer composition, and a balance of calcined dolomite.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1A is a photograph depicting a magnesium slag produced in Comparative Examples A, B and C; and

[0023] FIG. 1B is a photograph depicting a magnesium slag produced in Examples I, II and III.

DETAILED DESCRIPTION

[0024] The present disclosure will be further described in detail below with reference to examples.

Example I and Comparative Example A

[0025] Reagents used in Example I and Comparative Example A, and amounts thereof, are listed in Table 1.

TABLE-US-00001 TABLE 1 Reagents and amounts thereof used in Example I and Comparative Example A Reagents Calcined Boric dolomite/ Ferrosilicon/ Fluorite/ acid/ wt % wt % wt % wt % m x Example I 82.3 16.9 0.5 0.3 8 0.8 Comparative 80.9 16.6 2.5 0 — — Example A

[0026] In both Example I and Comparative Example A, calcined dolomite, ferrosilicon, fluorite and boric acid (only fluorite in the case of the Comparative Example A) were ground and mixed, and then briquetted. The briquettes so obtained were placed into a reduction retort, where the briquettes were heated to a temperature of about 1150 to about 1250° C. The reduction retort was evacuated to 13 Pa. The briquettes in the retort were subjected to that temperature for a period. After cooling, raw magnesium was collected.

[0027] It was found that Example I provided a raw magnesium yield which was 17% higher than that of the Comparative Example A. A composition analysis showed that the two examples provided similar Mg composition, which fully met the metallurgy magnesium industry standard. It was also found that the magnesium slag produced in Example I was in lump form and the slag produced in the Comparative Example A was in powder form, as shown in FIG. 1A and FIG. 1B.

Example II and Comparative Example B

[0028] Reagents used in Example II and Comparative Example B, and amounts thereof, are listed in Table 2.

TABLE-US-00002 TABLE 2 Reagents and amounts thereof used in Example II and Comparative Example B Reagents Calcined Boric dolomite/ Ferrosilicon/ Fluorite/ acid/ wt % wt % wt % wt % m x Example II 81.1 17.9 0.5 0.5 4 0.8 Comparative 81.0 16.5 2.5 0 — — Example B

[0029] In both Example II and Comparative Example B, calcined dolomite, ferrosilicon, fluorite and boric acid (only fluorite in the case of the Comparative Example B) were ground and mixed, and then briquetted. The briquettes so obtained were placed into a reduction retort, where the briquettes were heated to a temperature of about 1150 to 1250° C. The retort was evacuated as the same in Example I. The briquettes in the retort were subjected to that temperature for a period. After cooling, raw magnesium was collected.

[0030] It was found that Example II provided a raw magnesium yield which was 8% higher than that of the Comparative Example B. A composition analysis showed that the two examples provided similar Mg composition, which fully met the metallurgy magnesium industry standard. It was also found that the magnesium slag produced in Example II was in lump form and the slag produced in the Comparative Example B was in powder form, as shown in FIG. 1A and FIG. 1B.

Example III and Comparative Example C

[0031] Reagents used in Example III and Comparative Example C, and amounts thereof, are listed in Table 3.

TABLE-US-00003 TABLE 3 Reagents and amounts thereof used in Example III and Comparative Example C Reagents Calcined Boric dolomite/ Ferrosilicon/ Fluorite/ acid/ wt % wt % wt % wt % m x Example III 82.5 17.0 0 0.5 5 1 Comparative 80.9 16.6 2.5 0 — — Example C

[0032] The reagents were subjected to the same process as the above examples.

[0033] It was found that Example III provided a raw magnesium yield which was 12% less than that of the Comparative Example C, possibly due to the fact that the amount of the mineralizer is too small. A composition analysis showed that the two examples provided similar Mg composition. It was also found that the magnesium slag produced in Example III was in lump form and the slag produced in the Comparative Example C was in powder form, as shown in FIG. 1A and FIG. 1B.

[0034] While the present disclosure has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art.