Application method of 2-dodecanone and phenoxyacetyl chloride in reverse flotation of magnesite for desilication and decalcification

Abstract

The present invention provides a method for applying 2-dodecanone and phenoxyacetyl chloride in the reverse flotation of magnesite for desilication and decalcification. The specific process is as follows: Place the magnesite with high silicon, high calcium and low grade in a flotation device, add deionized water for mixing and stirring. After adjusting the pH value to 8.5-9.5, add the regulator 2-dodecanone to the pulp, stir, add the collector dodecylamine, stir evenly, and carry out the first reverse flotation to obtain the magnesite concentrate with partial silicon and calcium removed. After the first reverse flotation is completed, adjust the pH value to 7.5-8.5, add the regulator phenoxyacetyl chloride to the pulp, stir, add the collector dodecylamine, stir, and carry out the second reverse flotation to remove the remaining calcareous gangue dolomite and siliceous gangue quartz in the magnesite. This method can remove the calcareous gangue dolomite and siliceous gangue quartz in the magnesite, improve the quality of the magnesite concentrate, and provide a new method for the reverse flotation of magnesite for desilication and decalcification.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesite ore dressing and purification processes, and particularly relates to an application method of 2-dodecanone and phenoxyacetyl chloride in realizing reverse flotation desilication and decalcification of magnesite. Background Art

[0002] Magnesite is a carbonate mineral with industrial value. At present, with the continuous exploitation every year, the reserves of high-grade magnesite are getting less and less, while low-grade magnesite cannot be directly used as the raw material for calcining high-quality refractory magnesia. Through mineral processing technology, finding a suitable ore dressing and purification method for low-grade magnesite, improving the grade and recovery rate of MgO in the concentrate product, and reducing the content of silicon and calcium impurities are the inevitable directions for the development and utilization of magnesite resources. The main factor restricting the development and utilization of low-grade magnesite (MgO < 45%) is the relatively high content of silicon and calcium gangue in the ore. The silicon-containing gangue mainly includes silicate minerals such as quartz, talc, serpentine, tremolite, chlorite, etc., and the calcium-containing gangue mainly includes calcium carbonate minerals such as dolomite and calcite. And because dolomite (CaMg(CO3)2) and magnesite (MgCO3) are carbonate minerals belonging to the same trigonal crystal system, the similarity in crystal structure and elemental composition leads to unclear selectivity of reagents in the flotation process. At the same time, magnesite and dolomite surfaces will dissolve during the flotation process, resulting in a large amount of magnesium and calcium ions dissolving into the pulp. Since calcium and magnesium are alkaline earth metal elements in the same main group and have similar physical and chemical properties, the dissolved calcium and magnesium ions are prone to re-adsorb on the mineral surface under certain conditions to form magnesium carbonate, calcium carbonate, and calcium magnesium carbonate, changing the surface properties of the mineral and resulting in unclear selectivity of reagents in the flotation process. When manufacturing magnesia refractory materials, the impurity dolomite will form free CaO after calcination, and the free CaO is easy to hydrate and cause cracking of the brick blank; in addition, CaO will form low-melting-point silicates, weakening the strength of the refractory material. For example, the melting point of the formed calcio-olivine is 1498°C and the melting point of merwinite is 1550°C. The impurity quartz (SiO2) increases the brittleness of the material due to uneven distribution, resulting in uneven composition of the sintered product, greatly weakening the strength of the refractory material.

[0003] The flotation method is one of the main processes for treating magnesite ore. Generally, reverse flotation and direct flotation are used alternately, that is, first using amine collectors for reverse flotation to remove siliceous gangue minerals, and then using fatty acid collectors for direct flotation of magnesite. The flotation method has the characteristics of wide source of flotation reagents, low cost, and economic rationality. According to the characteristics of different magnesite ores, adopting a scientific ore dressing method, a reasonable process flow, and suitable ore dressing reagents can effectively separate magnesite from the siliceous gangue mineral quartz and the calcareous gangue mineral dolomite, realizing silicon reduction, calcium reduction, and magnesium enrichment, and finally obtaining high-purity magnesite concentrate.

[0004] In the current flotation purification of magnesite, it is relatively easy to remove siliceous gangue minerals, but it is difficult to remove calcareous gangue during the production process. Finding a suitable reagent for removing calcareous gangue minerals is the most important step in the current flotation purification of magnesite. The present invention mainly conducts research on how to efficiently remove silicon and calcium, and provides a method for reverse flotation of magnesite to remove silicon and calcium by adding 2-dodecanone and phenoxyacetyl chloride. Compared with existing research, the two regulators 2-dodecanone and phenoxyacetyl chloride found in the present invention have not been used in the reverse flotation of magnesite to remove silicon and calcium, and it has been proved that these two regulators can achieve a better effect of jointly removing siliceous and calcareous gangue. Summary of the Invention

[0005] The object of the present invention is to provide a method for reverse flotation of magnesite to remove silicon and calcium by adding the efficient regulators 2-dodecanone and phenoxyacetyl chloride. During the flotation process of magnesite, in the first step of reverse flotation, the regulator 2-dodecanone is added, and according to the floatability difference between magnesite and the gangue minerals dolomite and quartz in magnesite under the determined dosage of 2-dodecanone, part of the calcareous gangue dolomite and siliceous gangue quartz in magnesite are removed; in the second step of reverse flotation, the regulator phenoxyacetyl chloride is added, and according to the floatability difference between magnesite and the gangue minerals dolomite and quartz in magnesite under the determined dosage of phenoxyacetyl chloride, the remaining calcareous gangue dolomite and siliceous gangue quartz in magnesite are removed. Finally, the quality of magnesite concentrate is improved, providing a new method for the beneficiation of high-silicon, high-calcium and low-grade magnesite.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for realizing reverse flotation of magnesite to remove silicon and calcium, which uses the regulators 2-dodecanone and phenoxyacetyl chloride in the reverse flotation process of magnesite to remove silicon and calcium.

[0008] Furthermore, the 2-dodecanone and phenoxyacetyl chloride are directly added to the pulp for use.

[0009] Furthermore, it specifically includes the following steps:

[0010] Step 1: Select ore samples

[0011] Select high-silicon, high-calcium and low-grade magnesite powder with a particle size between 0.106 and 0.074 mm;

[0012] Step 2: Adjust the pulp

[0013] Place the ore powder in step 1 into a flotation device, add 45 mL of deionized water, mix evenly, and adjust the pulp to obtain a magnesite pulp;

[0014] Step 3: The first step of reverse flotation to remove silicon and calcium

[0015] Step 31: At room temperature, add NaOH solution or HCl solution to the magnesite pulp, adjust the pH value to 8.5 - 9.5, and then stir evenly to obtain a magnesite pulp with a pH value of 8.5 - 9.5.

[0016] Step 32: Add the regulator 2-dodecanone to the magnesite pulp with a pH value of 8.5 - 9.5 and stir evenly; wherein, by dosage ratio, regulator 2-dodecanone: magnesite pulp = (100 - 600) mg: 1 L.

[0017] Step 33: Then add the collector dodecylamine for the first stage of reverse flotation to obtain a magnesite concentrate with partial silicon and calcium removed; wherein, by dosage ratio, collector dodecylamine: magnesite pulp = (10 - 60) mg: 1 L.

[0018] Step 4: The second stage of reverse flotation for silicon and calcium removal

[0019] Step 41: At room temperature, continue to add NaOH solution or HCl solution to the magnesite pulp treated in Step 33, adjust the pH value to 7.5 - 8.5, and then stir evenly to obtain a magnesite pulp with a pH value of 7.5 - 8.5.

[0020] Step 42: Add the regulator phenoxyacetyl chloride to the magnesite pulp with a pH value of 7.5 - 8.5 and stir evenly; wherein, by dosage ratio, regulator phenoxyacetyl chloride: magnesite pulp = (100 - 600) mg: 1 L.

[0021] Step 43: Then add the collector dodecylamine for the second stage of reverse flotation to obtain a magnesite concentrate with low silicon and calcium content; wherein, by dosage ratio, collector dodecylamine: magnesite pulp = (10 - 60) mg: 1 L.

[0022] Furthermore, in the said Step 1, for the high-silicon, high-calcium and low-grade magnesite, its main components by weight percentage are: 30 - 44% MgO, 1 - 8% CaO, and 1 - 5% SiO2.

[0023] Furthermore, in the said Step 2, the preferred flotation equipment is a hanging cell flotation machine with a rotation speed of 1600 - 2000 rpm.

[0024] Furthermore, in the said Step 3, the dosage of the regulator 2-dodecanone preferably accounts for 400 mg / L of the magnesite pulp volume.

[0025] Furthermore, in the said Step 3, the preferred NaOH and HCl are NaOH and HCl aqueous solutions with a mass fraction of 1 - 5%.

[0026] Further, in the step 31, the mixture is stirred evenly at a stirring rate of 1600 - 2000 rpm for 2 - 5 min.

[0027] Further, in the step 31, the pH value is preferably pH = 9.

[0028] Further, in the step 3, in the first reverse flotation, the rotational speed of the flotation equipment is 1600 - 2000 rpm, preferably 1920 rpm, and the flotation time is 3 - 5 min, preferably 3 min.

[0029] Further, in the step 33, the dosage of the collector dodecylamine preferably accounts for 30 mg / L of the magnesite pulp.

[0030] Further, in the step 33, after adding the collector dodecylamine, it is stirred evenly and then reverse flotation is carried out finally.

[0031] Further, in the step 33, the main components of the magnesite concentrate with partial silicon and calcium removed are by weight percentage: MgO 40% - 45%, CaO ≤ 4%, SiO2 ≤ 4%.

[0032] Further, in the step 3, the recovery rate of MgO in the concentrate of the first reverse flotation of magnesite is 60% - 80% by weight percentage, the removal rate of CaO in the magnesite concentrate is 30% - 50% by weight percentage, and the removal rate of SiO2 in the magnesite concentrate is 40% - 60% by weight percentage.

[0033] Further, in the step 2, the flotation equipment is preferably a hanging trough flotation machine with a rotational speed of 1600 - 2000 rpm.

[0034] Further, in the step 4, the dosage of the regulator phenoxyacetyl chloride preferably accounts for 500 mg / L of the magnesite pulp.

[0035] Further, in the step 4, the NaOH and HCl are preferably NaOH and HCl aqueous solutions with a mass fraction of 1 - 5%.

[0036] Further, in the step 41, the mixture is stirred evenly at a stirring rate of 1600 - 2000 rpm for 2 - 5 min.

[0037] Further, in the step 41, the pH value is preferably pH = 8.

[0038] Further, in the step 4, in the second reverse flotation, the rotation speed of the flotation equipment is 1600-2000 rpm, preferably 1920 rpm, and the flotation time is 3-5 min, preferably 3 min.

[0039] Further, in the step 43, the dosage of the collector dodecylamine preferably accounts for 30 mg / L of the magnesite pulp.

[0040] Further, in the step 43, after adding the collector dodecylamine, it is stirred evenly, and finally reverse flotation is carried out.

[0041] Further, in the step 43, the main components of the low-silicon and low-calcium magnesite concentrate are calculated by weight percentage as follows: MgO 46.0%-47.5%, CaO≤1.00%, SiO2≤1.00%.

[0042] Further, in the step 4, the recovery rate of MgO in the concentrate of the second reverse flotation of magnesite is 55%-85% by weight percentage, the removal rate of CaO in the magnesite concentrate is 80%-95% by weight percentage, and the removal rate of SiO2 in the magnesite concentrate is 85%-98% by weight percentage.

[0043] The remarkable advantages of the present invention are as follows:

[0044] Compared with the currently more applied experimental methods for magnesite ore beneficiation and purification, that is, the characteristics of the reverse flotation for simple desilication or the reverse flotation desilication - forward flotation magnesium extraction process flow showing unclear reagent selectivity and poor concentrate quality, the method of the present invention can, in the reverse flotation system with dodecylamine as the collector, achieve the purpose of reverse flotation removal of calcareous gangue dolomite and siliceous gangue quartz from the artificial mixed ore of magnesite by stepwise adding two high-efficiency regulators, 2-dodecanone and phenoxyacetyl chloride, can greatly improve the reagent selection performance, obtain a better magnesite beneficiation and purification effect, and can bring better economic and social value to the reverse flotation desilication and decalcification of magnesite. Description of the Drawings

[0045] Figure 1 It is a flow chart of the application of 2-dodecanone and phenoxyacetyl chloride in the reverse flotation desilication and decalcification test of the artificial mixed ore of magnesite. Detailed Embodiments

[0046] To make the above features and advantages of the present invention more obvious and understandable, the following specific embodiments are given for detailed description. The methods of the present invention are all conventional methods in the art without special instructions.

[0047] Example 1

[0048] Step 1: Prepare ore samples

[0049] Prepare pure minerals of magnesite, dolomite and quartz, mix the three minerals in a certain proportion to prepare an artificial mixed ore; the particle size of the artificial mixed ore is between 0.106 and 0.074 mm; by mass ratio, the proportion of the artificial mixed ore is magnesite:dolomite:quartz = 36:3:1;

[0050] Step 2: Pulp preparation

[0051] Place the artificial mixed ore powder obtained in Step 1 into a hanging cell flotation machine, add 45 mL of deionized water, mix evenly, and perform pulp preparation to obtain a magnesite pulp;

[0052] Step 3: First reverse flotation for silicon and calcium removal

[0053] At room temperature, first add an aqueous solution of HCl or NaOH with a mass fraction of 1% to the magnesite pulp to adjust the pH value, stir for 2 min until the pulp is uniform, and obtain a magnesite pulp with a pH value of 9;

[0054] To the magnesite pulp with a pH value of 9, add the modifier 2-dodecanone, with an addition amount of 400 mg / L based on the amount of the magnesite pulp, and stir for 3 min; then add the collector dodecylamine, with an addition amount of 30 mg / L based on the amount of the magnesite pulp, stir for 3 min, and finally perform the first reverse flotation for 3 min to obtain a magnesite concentrate with reduced silicon and calcium. The MgO grade of this concentrate is 42.65%, the recovery rate is 70.58%; the CaO grade is 2.62%, and the removal rate is 34.90%; the SiO2 grade is 3.39%, and the removal rate is 42.88%. During the test process, the rotational speed of the flotation machine is set at 1920 rpm.

[0055] Step 4: Second reverse flotation for silicon and calcium removal

[0056] At room temperature, first add an aqueous solution of HCl or NaOH with a mass fraction of 1% to the magnesite pulp to adjust the pH value, stir for 2 min until the pulp is uniform, and obtain a magnesite pulp with a pH value of 8;

[0057] To the magnesite pulp with a pH value of 8, add the modifier phenoxyacetyl chloride, with an addition amount of 500 mg / L based on the amount of the magnesite pulp, and stir for 3 min; then add the collector dodecylamine, with an addition amount of 30 mg / L based on the amount of the magnesite pulp, stir for 3 min, and finally perform the second reverse flotation for 3 min to obtain a low-silicon and low-calcium magnesite concentrate. During the test process, the rotational speed of the flotation machine is set at 1920 rpm.

[0058] In this example, when the grades of MgO, CaO, and SiO2 in the raw ore are 42.60%, 2.84%, and 4.19% respectively, the concentrate indexes obtained are: MgO grade 46.95%, recovery rate 62.83%; CaO grade 0.65%, removal rate 86.95%; SiO2 grade 0.51%, removal rate 93.06%. That is, on the premise of ensuring the grade and recovery rate of magnesite concentrate, siliceous gangue quartz and calcareous gangue dolomite are preferably removed.

[0059] Example 2

[0060] Step 1: Prepare ore samples

[0061] Prepare pure minerals of magnesite, dolomite, and quartz, mix the three minerals in a certain proportion to prepare an artificial mixed ore; the particle size of the artificial mixed ore is between 0.106 and 0.074 mm; according to the mass ratio, the proportion of the artificial mixed ore is magnesite:dolomite:quartz = 34:4:2;

[0062] Step 2: Pulp adjustment

[0063] Put the artificial mixed ore powder obtained in Step 1 into a hanging trough flotation machine, add 45 mL of deionized water, mix evenly, and perform pulp adjustment to obtain magnesite pulp;

[0064] Step 3: First-stage reverse flotation for silicon and calcium removal

[0065] At room temperature, first add an aqueous solution of HCl or NaOH with a mass fraction of 1% to the magnesite pulp to adjust the pH value, stir for 2 min until the pulp is uniform, and obtain magnesite pulp with a pH value of 9;

[0066] To the magnesite pulp with a pH value of 9, add the modifier 2-dodecanone, and its addition amount accounts for 400 mg / L of the magnesite pulp, stir for 3 min; then add the collector dodecylamine, and its addition amount accounts for 30 mg / L of the magnesite pulp, stir for 3 min, and finally perform the first-stage reverse flotation for 3 min to obtain magnesite concentrate with reduced silicon and calcium. The concentrate has a MgO grade of 42.36%, a recovery rate of 67.25%; a CaO grade of 2.66%, a removal rate of 39.69%; a SiO2 grade of 3.22%, a removal rate of 49.31%. During the test, the rotational speed of the flotation machine is set at 1920 rpm.

[0067] Step 4: Second-stage reverse flotation for silicon and calcium removal

[0068] At room temperature, first add an aqueous solution of HCl or NaOH with a mass fraction of 1% to the magnesite pulp to adjust the pH value, stir for 2 min until the pulp is uniform, and obtain magnesite pulp with a pH value of 8;

[0069] To the magnesite pulp with a pH value of 8, the modifier phenoxyacetyl chloride was added, and its addition amount accounted for 500 mg / L of the magnesite pulp, and it was stirred for 3 min; then the collector dodecylamine was added, and its addition amount accounted for 30 mg / L of the magnesite pulp, and it was stirred for 3 min. Finally, the second-stage reverse flotation was carried out for 3 min to obtain a magnesite concentrate with low silicon and low calcium. During the test process, the rotational speed of the flotation machine was set at 1920 rpm.

[0070] In this embodiment, when the grades of MgO, CaO, and SiO2 in the raw ore were 42.20%, 2.96%, and 4.25% respectively, the concentrate indexes were obtained as follows: the grade of MgO was 46.19% and the recovery rate was 60.75%; the grade of CaO was 0.80% and the removal rate was 84.95%; the grade of SiO2 was 0.55% and the removal rate was 92.79%. That is, on the premise of ensuring the grade and recovery rate of the magnesite concentrate, the siliceous gangue quartz and calcareous gangue dolomite were preferably removed.

[0071] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A method for applying 2-dodecanone and phenoxyacetyl chloride in the reverse flotation of magnesite to remove silicon and calcium, characterized in that, The application method is to add the regulators 2-dodecanone and phenoxyacetyl chloride during the flotation process of magnesite. Due to the floatability difference between magnesite and the impurity minerals dolomite and quartz in magnesite, the silicon and calcium minerals in magnesite are removed. Specifically, it includes the following steps: Step 1: Select ore samples Select high-silicon, high-calcium, and low-grade magnesite powder with a particle size between 0.106 and 0.074 mm. Step 2: Pulp adjustment Place the ore powder from Step 1 into a flotation device, add 45 mL of deionized water, mix evenly, and perform pulp adjustment to obtain a magnesite pulp. Step 3: First-stage reverse flotation for silicon and calcium removal Step 31: At room temperature, add NaOH solution or HCl solution to the magnesite pulp, adjust the pH value to 8.5 - 9.5, and then stir evenly. Step 32: Add the regulator 2-dodecanone and stir evenly. Step 33: Then add the collector dodecylamine for the first-stage reverse flotation to obtain a magnesite concentrate with partial silicon and calcium removed. Step 4: Second-stage reverse flotation for silicon and calcium removal Step 41: At room temperature, add NaOH solution or HCl solution to the magnesite pulp, adjust the pH value to 7.5 - 8.5, and then stir evenly. Step 42: Add the regulator phenoxyacetyl chloride and stir evenly. Step 43: Then add the collector dodecylamine for the second-stage reverse flotation to obtain a low-silicon and low-calcium magnesite concentrate.

2. The application method according to claim 1, characterized in that, In Step 1, for the high-silicon, high-calcium, and low-grade magnesite, its main components by weight percentage are: MgO is 30 - 44%, CaO is 1 - 8%, and SiO2 is 1 - 5%.

3. The application method according to claim 1, characterized in that, In Step 31 and Step 41, the NaOH solution or HCl solution is an aqueous solution of NaOH or HCl with a mass fraction of 1 - 5%; the stirring rate is 1600 - 2000 rpm, and the stirring time is 2 - 5 min.

4. The application method according to claim 1, characterized in that, In Step 32, by dosage ratio, regulator 2-dodecanone:magnesite pulp = (100 - 600) mg:1 L.

5. The application method according to claim 1, characterized in that, In Step 33, during the first-stage reverse flotation, the rotation speed of the device is 1600 - 2000 rpm, and the reverse flotation time is 3 - 5 min; by dosage ratio, collector dodecylamine:magnesite pulp = (10 - 60) mg:1 L.

6. The application method according to claim 1, wherein In Step 33, for the magnesite concentrate with partial silicon and calcium removed, its main components by weight percentage are MgO grade 40% - 45%, CaO ≤ 4%, and SiO2 ≤ 4%.

7. The application method according to claim 1, characterized in that, In Step 42, by dosage ratio, regulator phenoxyacetyl chloride:magnesite pulp = (100 - 600) mg:1 L.

8. The application method according to claim 1, characterized in that, In Step 43, during the second-stage reverse flotation, the rotation speed of the device is 1600 - 2000 rpm, and the reverse flotation time is 3 - 5 min; by dosage ratio, collector dodecylamine:magnesite pulp = (10 - 60) mg:1 L.

9. The application method according to claim 1, characterized in that In Step 43, for the low-silicon and low-calcium magnesite concentrate, its main components by weight percentage are MgO grade 46.0% - 47.5%, CaO ≤ 1.00%, and SiO2 ≤ 1.00%.

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