WO2020155232A1

WO2020155232A1 - Method for decalcification of magnesite by flotation by means of egta and shmp synergistic inhibition

Info

Publication number: WO2020155232A1
Application number: PCT/CN2019/075794
Authority: WO
Inventors: 孙浩然; 印万忠; 唐远; 杨斌; 韩会丽; 姚金
Original assignee: 东北大学
Priority date: 2019-01-31
Filing date: 2019-02-22
Publication date: 2020-08-06
Also published as: CN109847947B; CN109847947A

Abstract

A method for decalcification of magnesite by flotation by means of EGTA and SHMP synergistic inhibition, comprising grinding, pulping, and direct flotation roughing decalcification. In the pulping, an inhibitor EGTA solution is added to magnesite slurry; and in the direct flotation roughing decalcification, an inhibitor SHMP is added to the magnesite slurry having a pH value of 10 to 12, and a collector and a foaming agent are added to perform the direct flotation roughing decalcification. According to the method, the difference in floatability of magnesite and impurity mineral dolomite under the synergistic effect of EGTA and SHMP is used to remove the calcium minerals in magnesite, thereby improving the quality of magnesite.

Description

Method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation

Technical field

The invention relates to the technical field of magnesite beneficiation and purification technology, in particular to a method for synergistic inhibition of EGTA and SHMP for magnesite flotation decalcification.

Background technique

In the process of magnesite beneficiation and purification, reducing the content of CaO is the key to improving the quality of magnesite. CaO in magnesite is mainly contained in impurity mineral dolomite (CaMg(CO ₃ ) ₂ ). At present, the main inhibitor used for the decalcification of magnesite is sodium hexametaphosphate. Sodium hexametaphosphate has less inhibitory effect on magnesite monominerals and greater inhibition on dolomite monominerals. However, due to the flotation process The dissolution of medium magnesite and dolomite minerals causes a large amount of magnesium and calcium ions to dissolve into the slurry, and the physical and chemical properties of calcium and magnesium ions are similar, causing calcium ions in the solution to be adsorbed to the surface of magnesite, prompting magnesite and dolomite The surface properties of the magnesite are the same, so that the magnesite is also inhibited by sodium hexametaphosphate, resulting in a lower recovery rate of the magnesite and increasing the difficulty of flotation separation. Therefore, a chelating agent with strong selectivity to calcium ions was found, which can form a chelate with Ca ²⁺ in the raw ore slurry, reduce the amount of Ca ²⁺ adsorbed by magnesite, and use sodium hexametaphosphate as an inhibitor. Under the separation system, it is imperative to increase the recovery rate of magnesite.

Summary of the invention

The purpose of the present invention is to provide a method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation, according to the combination of inhibitor EGTA (ethylene glycol bis(2-aminoethyl ether) tetraacetic acid) in different proportions + Under the dosage of SHMP (sodium hexametaphosphate), the difference in floatability of impurity mineral dolomite in magnesite and magnesite can remove calcium minerals in magnesite and improve the quality of magnesite. Low-grade calcium magnesite beneficiation decalcification provides a new agent.

The method for decalcification of magnesite flotation with EGTA and SHMP synergistic inhibition of the present invention includes grinding, slurry adjustment, and rough flotation decalcification;

In the slurry adjustment, the inhibitor EGTA solution is added to the magnesite slurry for slurry adjustment;

In the positive flotation rough decalcification, the inhibitor SHMP is added to the magnesite slurry whose pH is adjusted to 10-12, and the subsequent positive flotation rough decalcification is performed.

In the method of synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation, according to the solid-liquid ratio, EGTA: magnesite slurry = (40-80) mg: 1L, according to the solid-liquid ratio, SHMP: magnesite Magnesite slurry=(30-50)mg:1L; among them, the mass concentration of magnesite powder in the magnesite slurry is 20-40%.

The inhibitor EGTA solution is an inhibitor solution with a mass concentration of 0.5-1.5 g/L prepared by using deionized water with a pH of 10-12.

The inhibitor SHMP can be formulated into an inhibitor SHMP solution for use, and the mass concentration of the inhibitor SHMP solution is preferably 1.0-2.5 g/L.

In the method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation, the grinding is:

The high-calcium and low-grade magnesite is crushed and ball-milled to obtain magnesite powder; wherein, in the magnesite powder, the mass of the magnesite powder with a particle size of <74 μm accounts for 75-85% of the total mass of the magnesite powder.

Said grinding, said low-grade calcium magnesite, its main component and various ingredients in percent by weight MgO, 20 ~ 30%, CaO is 20 ~ 30%, SiO ₂ 0 to 0.5%.

In the method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation, the slurry adjustment is specifically:

Place the magnesite powder in a flotation device, add deionized water and inhibitor EGTA solution, mix them evenly, and perform slurry adjustment to obtain a magnesite slurry with a mass concentration of 20-40%.

In the slurry adjustment, the flotation equipment is preferably a hanging trough flotation machine with a rotation speed of 1600-1900 rpm.

In the slurry adjustment, the amount of the inhibitor EGTA in the magnesite slurry is preferably 50 mg/L.

In the method for synergistic inhibition of EGTA and SHMP for decalcification by flotation of magnesite, the rough decalcification by positive flotation is specifically:

1) At room temperature, add NaOH to the magnesite slurry, adjust the pH to 10-12, and stir evenly to obtain a magnesite slurry with a pH of 10-12;

2) Add inhibitor SHMP to the magnesite slurry with a pH value of 10-12, and after mixing uniformly, add the collector sodium oleate, stir uniformly, and then perform rough flotation decalcification to obtain low-calcium magnesite Magnesium ore concentrate; among them, according to the solid-liquid ratio, the collector sodium oleate in the aqueous solution of collector sodium oleate: magnesite slurry = (100 ~ 140) mg:1L.

In the method for synergistic inhibition of EGTA and SHMP of the present invention for decalcification of magnesite flotation, EGTA and SHMP are used together as inhibitors for the process of decalcification of magnesite flotation.

In the positive flotation rough decalcification, the NaOH is preferably an aqueous NaOH solution with a mass fraction of 1 to 5%.

In the rough flotation decalcification, the amount of the inhibitor sodium hexametaphosphate based on the amount of the magnesite slurry is preferably 40 mg/L.

In the positive flotation rough decalcification, the stirring is uniform, the stirring speed is 1600-1900 rpm, and the stirring time is 2-5 min.

In the positive flotation rough decalcification, the pH value is preferably 11.

In the positive flotation rough decalcification, the rotation speed of the positive flotation device is 1600-1900 rpm, preferably 1800 rpm, and the positive flotation time is preferably 3-5 min.

In the positive flotation crude decalcification, the collector sodium oleate is preferably an aqueous sodium oleate solution with a molar concentration of 0.01-0.05 mol/L.

In the rough flotation decalcification, the amount of the collector sodium oleate in the amount of the magnesite slurry is preferably 120 mg/L.

In the positive flotation rough decalcification, after adding the collector sodium oleate, a foaming agent is added, stirred uniformly, and finally positive flotation rough decalcification is performed. The foaming agent is preferably 2 No. 2 oil, according to the solid-liquid ratio, No. 2 oil: magnesite slurry = (4 ~ 6) mg: 1L.

In the positive flotation rough decalcification, the main components and individual components of the low-calcium magnesite concentrate are MgO 47.5 to 48.5%, SiO ₂ ≤0.3%, and CaO≤0.6% by weight.

The EGTA and SHMP of the present invention synergistically inhibit the method for decalcification of magnesite flotation, the recovery rate of the low-calcium magnesite concentrate is 70-85% by weight, and the MgO in the low-calcium magnesite concentrate The recovery rate is 65-75% by weight.

Compared with the prior art, the method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation of the present invention has the following beneficial effects:

1. The present invention develops the use of a new inhibitor EGTA. Because the new inhibitor EGTA has strong selectivity for calcium ions in the solution, it can generate calcium-containing complexes, thereby reducing the effect of magnesite on calcium ions in the solution. Adsorption reduces the inhibition of magnesite by sodium hexametaphosphate inhibitor. Compared with adding sodium hexametaphosphate as the inhibitor, adding EGTA+sodium hexametaphosphate can significantly increase the recovery rate of magnesite in the concentrate. Finally, a magnesite concentrate with an MgO grade greater than 47% and a recovery rate of 80-90% can be obtained.

2. Compared with the prior art, the ore processed by the method of the present invention is of low grade and the content of CaO in the raw ore is high; the obtained magnesite concentrate can reach the special grade standard (YB321～81) of the metallurgical industry, namely MgO≥47.00 %, SiO ₂ ≤0.30%, CaO≤0.8%.

3. The new inhibitor EGTA (ethylene glycol bis(2-aminoethyl ether) tetraacetic acid) in the present invention is a complexing agent with strong calcium selectivity. It is chemically mainly used to measure the solution in the presence of magnesium ions. The titration agent for the content of calcium ions in the magnesite. Since EGTA can form hydrophilic complexes with calcium ions, it is used as a medicament to prevent the adsorption of calcium ions in the slurry solution by magnesite during the decalcification process of magnesite , So as to improve the flotation recovery rate of magnesite, and provide a new inhibitor for the decalcification of low-grade magnesite.

Description of the drawings

Fig. 1 is a schematic diagram of the process flow of the method for synergistic inhibition of EGTA and SHMP in Example 1 of the present invention for decalcification by flotation of magnesite.

Figure 2 is the XRD pattern of the raw material magnesite of the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the embodiments.

In the following examples, the high-calcium and low-grade magnesite used is Shuidonggou magnesite in Kuandian, Liaoning. The elemental composition of the high-calcium and low-grade magnesite is analyzed by X-ray fluorescence spectrometry. The main components are The weight percentages are: MgO is 33.58%, SiO _{2 is} 0.27%, CaO is 15.17%, and the balance is CO ₂ and unavoidable impurities; the XRD pattern is shown in Figure 2. The inhibitors EGTA (ethylene glycol bis(2-aminoethyl ether) tetraacetic acid) and SHMP (sodium hexametaphosphate) are analytically pure, the collector sodium oleate is chemically pure, and the pH adjuster sodium hydroxide is Analytical pure. All reagents used in the experiment were prepared with deionized water to prepare aqueous solutions of corresponding concentrations.

Example 1

A method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation is shown in Fig. 1, and includes the following steps:

Step 1: Grinding

The high-calcium and low-grade magnesite raw materials are crushed and ball milled to obtain magnesite powder; among them, the mass of magnesite powder with a size of less than 74μm accounts for 75% of the total mass of magnesite powder ；

Step 2: Mix the pulp

(1) Add NaOH to deionized water to obtain deionized water with a pH of 10, which is prepared with deionized water with a pH of 10 to obtain a mass concentration of 0.5 g/L;

(2) Put the magnesite powder whose size is less than 74μm and account for 75% of the total magnesite powder mass in a hanging trough flotation machine, add deionized water and inhibitor EGTA solution, among which, press solid-liquid Ratio, inhibitor EGTA: magnesite pulp=40mg:1L, and mix it evenly, and adjust the slurry to obtain magnesite slurry; where the mass concentration of magnesite in the magnesite slurry is 20%;

Step 3: Rough flotation decalcification

At room temperature, first add a 3% NaOH aqueous solution to the magnesite slurry, adjust the pH to 11, and stir for 2 minutes until the slurry is uniform to obtain a magnesite slurry with a pH of 11;

To the magnesite slurry with a pH of 11, first add an aqueous solution of inhibitor sodium hexametaphosphate with a mass concentration of 1 mg/L, and after stirring, add a collector oil with a molar concentration of 0.05 mol/L of the sodium oleate aqueous solution Sodium aqueous solution, where sodium hexametaphosphate accounts for 30mg/L of magnesite slurry, sodium oleate accounts for 100mg/L of magnesite slurry, stir for 2min, then add foaming agent No. 2 oil , The amount of No. 2 oil added accounts for 5mg/L of the magnesite slurry, stirred for 2 minutes, and finally undergoes 3 minutes of positive flotation for rough decalcification to obtain a low-calcium magnesite concentrate. During the test, set the flotation machine speed to 1800r/min.

In this embodiment, the main components of the low-calcium magnesite concentrate are 47.23% by weight of MgO, 0.25% of SiO ₂ and 0.59% of CaO; the MgO in the low-calcium magnesite concentrate accounts for the total MgO in the raw material. 80.25% of weight.

Example 2

Step 1: Grinding

The high-calcium and low-grade magnesite raw materials are crushed and ball milled to obtain magnesite powder; among them, the mass of magnesite powder with a size of less than 74μm accounts for 80% of the total mass of magnesite powder ；

Step 2: Mix the pulp

(1) Add NaOH to deionized water to obtain deionized water with a pH of 11, which is prepared with deionized water with a pH of 11 to obtain a mass concentration of 1g/L;

(2) Put the magnesite powder with a particle size of less than 74μm and account for 80% of the total magnesite powder mass in a hanging trough flotation machine, add deionized water and inhibitor EGTA solution, among which, press solid-liquid Ratio, inhibitor EGTA: magnesite pulp=50mg:1L, and mix it evenly, and adjust the slurry to obtain magnesite slurry; wherein the mass concentration of magnesite in the magnesite slurry is 20%;

Step 3: Rough flotation decalcification

At room temperature, first add 3% NaOH aqueous solution to the magnesite slurry, adjust the pH to 10, and stir for 2 minutes until the slurry is uniform to obtain a magnesite slurry with a pH of 10;

To the magnesite slurry with a pH of 11, first add an aqueous solution of inhibitor sodium hexametaphosphate with a mass concentration of 1.5 mg/L, and after stirring, add a collector with a molar concentration of 0.05 mol/L of sodium oleate solution Sodium oleate aqueous solution, in which sodium hexametaphosphate accounts for 40mg/L of magnesite slurry, and sodium oleate accounts for 110mg/L of magnesite slurry. Stir for 2min, then add foaming agent No. 2 Oil, the amount of No. 2 oil added accounted for 6mg/L of magnesite slurry, stirred for 2 minutes, and finally subjected to rough flotation decalcification for 3 minutes to obtain low calcium magnesite concentrate. During the test, set the speed of the flotation machine to 1700r/min.

In this embodiment, the main components of the low-calcium magnesite concentrate are 48.13% by weight of MgO, 0.14% of SiO ₂ and 0.61% of CaO; the MgO in the low-calcium magnesite concentrate accounts for the total MgO in the raw material. 80.25% of weight.

Example 3

Step 1: Grinding

The high-calcium and low-grade magnesite raw materials are crushed and ball milled to obtain magnesite powder; among them, the mass of magnesite powder with a particle size of less than 74μm accounts for 85% of the total mass of magnesite powder ；

Step 2: Mix the pulp

(1) Add NaOH to deionized water to obtain deionized water with a pH of 12, and prepare with deionized water with a pH of 12 to obtain a mass concentration of 1g/L;

(2) Put the magnesite powder with a size of less than 74μm and account for 85% of the total magnesite powder mass in a hanging trough flotation machine, add deionized water and inhibitor EGTA solution, among which, press solid-liquid Ratio, inhibitor EGTA: magnesite pulp=60mg:1L, and mix it evenly, and adjust the slurry to obtain magnesite slurry; wherein, the mass concentration of magnesite in the magnesite slurry is 25%;

Step 3: Rough flotation decalcification

At room temperature, first add 4% NaOH aqueous solution to the magnesite slurry, adjust the pH to 12, and stir for 2 minutes until the slurry is uniform to obtain a magnesite slurry with a pH of 12;

To the magnesite slurry with a pH of 12, first add an aqueous solution of inhibitor sodium hexametaphosphate with a mass concentration of 2 mg/L, and after stirring, add a collector oil with a molar concentration of 0.06 mol/L of the sodium oleate aqueous solution Sodium aqueous solution, in which sodium hexametaphosphate accounts for 50mg/L of magnesite slurry, sodium oleate accounts for 120mg/L of magnesite slurry, stir for 2min, and then add foaming agent No. 2 oil , The amount of No. 2 oil added accounts for 4mg/L of the magnesite slurry, stirred for 2 minutes, and finally undergoes 3 minutes of positive flotation for rough decalcification to obtain a low-calcium magnesite concentrate. During the test, set the speed of the flotation machine to 1600r/min.

In this embodiment, the main components of the low-calcium magnesite concentrate are 47.73% by weight of MgO, 0.22% of SiO ₂ and 0.19% of CaO; the MgO in the low-calcium magnesite concentrate accounts for the total MgO in the raw material. 81.25% of weight.

Example 4

Step 1: Grinding

The high-calcium and low-grade magnesite raw materials are crushed and ball milled to obtain magnesite powder; among them, the mass of magnesite powder with a size of less than 74μm accounts for 83% of the total mass of magnesite powder ；

Step 2: Mix the pulp

(1) Add NaOH to deionized water to obtain deionized water with a pH of 11, and prepare with deionized water with a pH of 11 to obtain a mass concentration of 1.5 g/L;

(2) Put the magnesite powder whose size is less than 74μm and account for 83% of the total magnesite powder mass in a hanging trough flotation machine, add deionized water and inhibitor EGTA solution, among which, press solid-liquid Ratio, inhibitor EGTA: magnesite pulp=70mg:1L, and mix it evenly, and adjust the slurry to obtain magnesite slurry; wherein the mass concentration of magnesite in the magnesite slurry is 35%;

Step 3: Rough flotation decalcification

At room temperature, first add a 4% NaOH aqueous solution to the magnesite slurry, adjust the pH to 11, and stir for 2 minutes until the slurry is uniform to obtain a magnesite slurry with a pH of 11;

To the magnesite slurry with a pH value of 11, first add an aqueous solution of inhibitor sodium hexametaphosphate with a mass concentration of 2.5 mg/L, and after stirring, add a collector with a molar concentration of 0.06 mol/L of sodium oleate solution Sodium oleate aqueous solution, in which sodium hexametaphosphate accounts for 40mg/L of magnesite slurry and sodium oleate accounts for 130mg/L of magnesite slurry. Stir for 2min, then add foaming agent No. 2 Oil, the amount of No. 2 oil added accounts for 4mg/L of magnesite slurry, stirring for 2min, and finally 3min positive flotation roughing decalcification to obtain low calcium magnesite concentrate. During the test, set the speed of the flotation machine to 1900r/min.

In this example, the main components of the low-calcium magnesite concentrate are 48.05% by weight of MgO, 0.25% of SiO ₂ and 0.39% of CaO; the MgO in the low-calcium magnesite concentrate accounts for the total MgO in the raw material. 87.69% of weight.

Example 5

A method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation is the same as in Example 1, except that according to the solid-liquid ratio, the inhibitor EGTA: magnesite pulp = 50mg:1L, the inhibitor six Sodium metaphosphate: magnesite pulp=40mg:1L, the main components of the obtained low-calcium magnesite concentrate are 47.23% by weight of MgO, 0.13% of SiO ₂ and 0.59% of CaO; low-calcium magnesite The MgO in the concentrate accounts for 88.15% of the total weight of MgO in the raw materials.

Example 6

A method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation is the same as in Example 1, except that according to the solid-liquid ratio, the inhibitor EGTA: magnesite pulp = 60mg:1L, the inhibitor six Sodium metaphosphate: magnesite pulp=40mg:1L, the main components of the obtained low-calcium magnesite concentrate are 47.73% by weight of MgO, 0.09% of SiO ₂ and 0.39% of CaO; low-calcium magnesite The MgO in the concentrate accounts for 86.35% of the total weight of MgO in the raw materials.

Example 7

A method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation is the same as in Example 1, except that according to the solid-liquid ratio, the inhibitor EGTA: magnesite pulp = 70mg:1L, the inhibitor six Sodium metaphosphate: magnesite pulp=50mg:1L, the main components of the obtained low-calcium magnesite concentrate are 48.23% by weight of MgO, 0.11% of SiO ₂ and 0.42% of CaO; low-calcium magnesite The MgO in the concentrate accounts for 89.15% of the total weight of MgO in the raw materials.

Example 8

A method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation is the same as in Example 2, except that in the magnesite powder, the mass of the magnesite powder whose size is less than 74μm accounts for the total magnesite 75% of the quality of the ore powder; the main components of the obtained low-calcium magnesite concentrate are 48.61% by weight of MgO, 0.21% of SiO ₂ and 0.27% of CaO; the MgO in the low-calcium magnesite concentrate accounts for 86.26% of the total weight of MgO in the raw materials.

Example 9

A method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation is the same as in Example 3, except that in the magnesite powder, the mass of the magnesite powder with a particle size of less than 74 μm accounts for the total magnesite 80% of the quality of the ore powder; the main components of the obtained low-calcium magnesite concentrate are 47.91% by weight of MgO, 0.11% of SiO ₂ and 0.29% of CaO; the MgO in the low-calcium magnesite concentrate accounts for 84.26% of the total weight of MgO in the raw materials.

Example 10

A method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation is the same as in Example 4, the difference is that in the magnesite powder, the mass of the magnesite powder whose size is less than 74μm accounts for the total magnesite 75% of the quality of the ore powder; the main components of the obtained low-calcium magnesite concentrate are 49.01% by weight of MgO, 0.21% of SiO ₂ and 0.07% of CaO; the MgO in the low-calcium magnesite concentrate accounts for 89.06% of the total weight of MgO in the raw materials.

Claims

A method for synergistic inhibition of EGTA and SHMP for flotation decalcification of magnesite, including grinding, slurry adjustment, and rough flotation decalcification, characterized in that, in the slurry adjustment, the inhibitor EGTA solution Adding to the magnesite slurry for slurry adjustment; in the positive flotation roughing decalcification, the inhibitor SHMP is added to the magnesite slurry whose pH is adjusted to 10-12 for subsequent positive flotation roughing decalcification calcium;

According to the solid-liquid ratio, EGTA: magnesite slurry=(40～80)mg:1L, according to the solid-liquid ratio, SHMP: magnesite slurry=(30～50)mg:1L; among them, in the magnesite slurry, The mass concentration of magnesite powder is 20-40%.
The method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation according to claim 1, wherein the inhibitor EGTA solution is prepared by using deionized water with a pH value of 10-12 An inhibitor solution with a mass concentration of 0.5 to 1.5 g/L.
The method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation according to claim 1, wherein the inhibitor SHMP is formulated as an inhibitor SHMP solution for use, and the mass concentration of the inhibitor SHMP solution is 1.0～2.5g/L.
The method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation as claimed in claim 1, wherein the synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation method, The grinding mentioned is:

The high-calcium low-grade magnesite is crushed and ball-milled to obtain magnesite powder; among them, the mass of the magnesite powder with a particle size of <74 μm accounts for 75-85% of the total magnesite powder mass.
The method for synergistically inhibiting EGTA and SHMP for decalcification of magnesite flotation according to claim 4, characterized in that, in the grinding, the high-calcium low-grade magnesite has its main components and respective components in percentage by weight of MgO, 20 ~ 30%, CaO is 20 ~ 30%, SiO 2 0 to 0.5%.
The method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation according to claim 1, wherein the synergistic inhibition of EGTA and SHMP for the method for decalcification of magnesite flotation, The above-mentioned mixing is specifically:

Place the magnesite powder in a flotation device, add deionized water and inhibitor EGTA solution, mix them evenly, and perform slurry adjustment to obtain a magnesite slurry with a mass concentration of 20-40%.
The method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation according to claim 1, wherein the synergistic inhibition of EGTA and SHMP for the method for decalcification of magnesite flotation, The rough flotation decalcification described is specifically:

1) At room temperature, add NaOH to the magnesite slurry, adjust the pH to 10-12, and stir evenly to obtain a magnesite slurry with a pH of 10-12;

2) Add inhibitor SHMP to the magnesite slurry with a pH value of 10-12, and after mixing uniformly, add the collector sodium oleate, stir uniformly, and then perform rough flotation decalcification to obtain low-calcium magnesite Magnesium ore concentrate; among them, according to the solid-liquid ratio, the collector sodium oleate in the aqueous solution of collector sodium oleate: magnesite slurry = (100 ~ 140) mg:1L.
The method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation according to claim 7, characterized in that, in the rough flotation decalcification of positive flotation, after adding the collector sodium oleate, Then add the foaming agent, stir evenly, and finally carry out positive flotation for rough decalcification. The foaming agent is No. 2 oil, according to the solid-liquid ratio, No. 2 oil: magnesite slurry = (4-6) mg : 1L.
The method for synergistic inhibition of EGTA and SHMP for decalcification by flotation of magnesite according to claim 7 or 8, characterized in that, in the rough flotation decalcification of positive flotation, the NaOH is 1～5% NaOH aqueous solution;

The stirring is uniform, the stirring speed is 1600-1900 rpm, the stirring time is 2 to 5 minutes, and the positive flotation time is 3 to 5 minutes;

The collector sodium oleate is an aqueous sodium oleate solution with a molar concentration of 0.01 to 0.05 mol/L.
The method for decalcification of magnesite flotation with EGTA and SHMP as claimed in claim 7 or 8, characterized in that, in the rough flotation decalcification of magnesite, the low calcium magnesite The main components and individual components of the concentrate are MgO 47.5～48.5% by weight, SiO 2 ≤0.3%, and CaO≤0.6%.
The method for synergistic inhibition of EGTA and SHMP for decalcification of magnesite flotation according to any one of claims 1 to 7, wherein the synergistic inhibition of EGTA and SHMP is used for decalcification of magnesite flotation In the method, the recovery rate of the low-calcium magnesite concentrate is 70-85% by weight, and the recovery rate of MgO in the low-calcium magnesite concentrate is 65-75% by weight.