Method for preparing porous calcium carbonate by using magnesium smelting reducing slag

Abstract

The invention discloses a method for preparing porous calcium carbonate by using magnesium smelting reducing slag, and relates to a comprehensive utilization method of magnesium smelting reducing slag, which is realized by the following steps of: (1) efficiently extracting a calcium component in the magnesium smelting reducing slag in the form of calcium ions by using a calcium extracting agent solution; and (2) carrying out carbonization treatment on the extracted calcium ions by controlling conditions to obtain the porous calcium carbonate. According to the method, the problems that a large amount of solid waste generated in the magnesium smelting industry cannot be treated and environmental pollution is caused are solved, environmental protection and high-value utilization of calcium resources in the magnesium smelting reducing slag are developed, the development concept of green chemical industry is met, and valuable reference prospects are provided for solid waste treatment and economic benefit point broadening in the magnesium smelting industry.

Description

Technical Field

[0001] The invention relates to a method for comprehensive utilization of magnesium smelting reduction slag, and in particular to a method for preparing porous calcium carbonate by utilizing magnesium smelting reduction slag. Background Art

[0002] Magnesium is one of the most abundant light metal elements on earth. my country's magnesium ore reserves rank first in the world, accounting for about 2 / 3 of the world's magnesium ore reserves, and about 1 / 2 of the world's light-burned magnesium production is provided by my country.

[0003] Raw magnesium can be obtained by refining resources such as magnesium ore, salt lakes and seawater. Its application is mainly concentrated in the fields of magnesium alloys and steelmaking desulfurization. It can also be used in rare earth alloys, metal reduction, corrosion protection and other fields. Magnesium resources have been included in the category of 46 strategic mineral resources in my country. At the same time, my country's magnesium industry also faces some problems that need to be solved urgently, especially the large amount of waste generated in the magnesium smelting process cannot be effectively treated or utilized, which has a serious impact on the environment.

[0004] The main process for obtaining raw magnesium in my country is the ferrosilicon reduction method, which mainly reduces dolomite calcined powder with ferrosilicon powder at high temperature to obtain crude magnesium and discharge magnesium reduction slag rich in calcium and silicon mixture. However, in addition to generating noise and waste heat, the above-mentioned magnesium smelting process also discharges a large amount of waste slag into the environment. Every ton of crude magnesium produced will produce 6-7 tons of magnesium reduction slag, and every ton of refined magnesium produced will also produce about 0.15-0.25 tons of refining flux slag.

[0005] At present, the research on magnesium reduction slag mainly involves cement, refractory materials, calcium magnesium silicon compound fertilizer and other fields. The processing volume of magnesium reduction slag is still far less than its output. Most of the magnesium reduction slag is still treated by stacking or landfill. The reduction slag leaching liquid is alkaline and corrosive, occupying a large amount of land and also facing the hazards of soil alkalinization. The development of high-value and environmentally friendly utilization technology of magnesium reduction slag and the development of new economic benefits are the current development direction of the magnesium industry. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing porous calcium carbonate by utilizing magnesium smelting reduction slag, wherein the method converts the magnesium smelting reduction slag into a chemical product with high added value, utilizes a calcium extracting agent to efficiently extract most of the calcium components in the magnesium smelting reduction slag in the form of calcium ions, and then obtains porous calcium carbonate by carbonization treatment, which is used in the fields of drug carriers, adsorption materials, papermaking industry, etc., so that the magnesium smelting reduction slag becomes a good raw material for producing chemical products with high added value, which can effectively solve the treatment problem of magnesium smelting reduction slag and has good economic prospects.

[0007] The technical solution adopted by the present invention is: A method for preparing porous calcium carbonate using magnesium smelting reduction slag comprises the following steps: a. Mixing magnesium reduction slag of a certain particle size with a certain amount of calcium extracting agent solution and adding them to the reactor, and connecting the reactor to the tail gas absorption unit; b. The magnesium smelting reduction slag reacts with the calcium extracting agent solution at a certain temperature. After the reaction is completed, the mixture is filtered to obtain a leaching solution rich in calcium ions; c. Take the calcium ion-rich leachate, introduce a certain amount of carbon dioxide gas into it at a certain temperature, stop introducing carbon dioxide when the system is neutral and age it, and then obtain porous calcium carbonate by suction filtration.

[0008] The main components of the magnesium smelting reduction slag in step a above include dicalcium silicate, magnesium oxide, and iron compounds, with mass fractions of 70%-80%, 1%-5%, and 10%-15% respectively, wherein the iron compounds include calcium ferrite and ferroferric oxide. But not limited thereto; The particle size of the magnesium smelting reduction slag described in step a is 100-300 mesh; The calcium extracting agent described in step a above is ammonium acetate or glycine; The concentration of the calcium extracting agent solution in step a is 80-400 g / L; The reaction temperature in step b is 40-100°C; The ratio of the amount of carbon dioxide introduced in step c to the amount of calcium ions in the leaching solution used is 1:1-3:1; The reaction temperature in the above step c is 5-35°C.

[0009] Advantages and effects of the present invention: (1) The present invention can efficiently and selectively extract the calcium component from magnesium smelting reduction slag. The obtained calcium component exists in the form of calcium salt solution and is easy to use.

[0010] (2) The porous calcium carbonate prepared by the present invention has a regular morphology, a controllable crystal form, a uniform particle size, good dispersion, high purity, and broad application prospects, thereby realizing the effective utilization of the calcium component in the magnesium smelting reduction slag.

[0011] (3) The process of the present invention is simple, the conditions are mild, and it is easy to realize large-scale production. The tail gas NH3 generated during the reaction and the calcium extracting agent in the filtrate after preparing the porous calcium carbonate can be recovered and recycled, which can effectively reduce the generation of "three wastes".

[0012] (4) The present invention provides a high-value utilization method for magnesium smelting reduction slag, which can effectively solve the problem of magnesium smelting solid waste treatment, improve the comprehensive utilization rate of resources, reduce environmental pollution, and is expected to bring new economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a flow chart of a method for preparing porous calcium carbonate using magnesium smelting reduction slag according to the present invention; Figure 2 The XRD diagram of the sieved magnesium reduction slag powder of the present invention; Figure 3 This is a SEM image of porous calcium carbonate prepared at 5°C in the present invention; Figure 4 This is a SEM image of porous calcium carbonate prepared at 25°C in the present invention; Figure 5 The XRD diagram of the porous calcium carbonate prepared at 5°C and 25°C in the present invention. DETAILED DESCRIPTION

[0014] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0015] It should be noted that in the following embodiments, the magnesium reduction slag used is tested to contain 70%-80% dicalcium silicate, 1%-5% magnesium oxide, and 10%-15% iron compounds by mass, wherein the iron compounds include calcium ferrite and ferrosoferric oxide. But it is not limited to this; Example

[0016] As attached Figure 1 As shown, the present invention uses magnesium smelting reduction slag to prepare porous calcium carbonate, and the method includes the following specific steps: S1, extracting calcium components from magnesium smelting reduction slag; S2. Prepare porous calcium carbonate.

[0017] The process of extracting calcium components from magnesium reduction slag in S1 is as follows: (1) sieve the magnesium reduction slag through a 300-mesh screen to obtain fine magnesium reduction slag powder; (2) weigh 100 g of ammonium acetate solid and deionized water to prepare 800 mL of ammonium acetate solution; (3) weigh 20 g of magnesium reduction slag powder, add it to the above ammonium acetate solution, connect the tail gas absorption device, and react at 45 °C for 60 min; (4) filter the magnesium reduction slag suspension obtained after the reaction to obtain the required calcium ion-rich leaching solution. It has been determined that the calcium extraction rate can reach more than 85%.

[0018] The process of preparing porous calcium carbonate in S2 is as follows: (1) taking 400 mL of the calcium ion-rich leachate described in S1, introducing carbon dioxide gas into the leachate at a reaction temperature of 5 °C and a stirring rate of 300 r / min, and the aeration rate is 100 mL / min. When the leachate is neutral, the introduction of carbon dioxide gas is stopped and aging is continued for 60 min; (3) after filtration, washing and drying, porous calcium carbonate is obtained. The average particle size D of the porous calcium carbonate product is determined to be 50 The surface area is about 3.08 μm, and the BET specific surface area is 10.67 m 2 / g, pore volume 0.064 cm 3 / g, purity is 96%, and calcium conversion rate is 41%. Example 1

[0019] As attached Figure 1 As shown, the present invention uses magnesium smelting reduction slag to prepare porous calcium carbonate, and the method includes the following specific steps: S1, extracting calcium components from magnesium smelting reduction slag; S2. Prepare porous calcium carbonate.

[0020] The process of extracting calcium components from magnesium reduction slag in S1 is as follows: (1) sieve the magnesium reduction slag through a 300-mesh screen to obtain fine magnesium reduction slag powder; (2) weigh 100 g of ammonium acetate solid and deionized water to prepare 800 mL of ammonium acetate solution; (3) weigh 20 g of magnesium reduction slag powder, add it to the above ammonium acetate solution, connect the tail gas absorption device, and react at 45 °C for 60 min; (4) filter the magnesium reduction slag suspension obtained after the reaction to obtain the required calcium ion-rich leaching solution. It has been determined that the calcium extraction rate can reach more than 85%.

[0021] The process of preparing porous calcium carbonate in S2 is as follows: (1) taking 400 mL of the calcium ion-rich leaching solution described in S1, introducing carbon dioxide gas into the leaching solution at a reaction temperature of 25 °C and a stirring rate of 300 r / min, and the aeration rate is 100 mL / min. When the leaching solution is neutral, the introduction of carbon dioxide gas is stopped and aging is continued for 60 min; (3) after filtration, washing and drying, porous calcium carbonate is obtained. It is determined that the average particle size D of the porous calcium carbonate product is 50 The surface area is about 2.63 μm, and the BET specific surface area is 6.65 m 2 / g, pore volume 0.066 cm 3 / g, purity is 96%, and calcium conversion rate is 62%.

[0022] Figure 2It is shown that the main components of the magnesium smelting reduction slag used in the present invention are stable γ-phase dicalcium silicate, magnesium oxide, calcium ferrite and ferrosoferric oxide after cooling and pulverization.

[0023] Figure 3 It shows that the porous calcium carbonate spheres prepared in Example 1 are relatively uniform in size, small calcium carbonate particles grow evenly on the surface, and tiny pores exist.

[0024] Figure 4 It shows that the porous calcium carbonate spheres prepared in Example 2 have regular morphology, uniform size, good dispersion, cracked surface, and the pore diameter and pore depth are significantly larger than those of the porous calcium carbonate prepared in Example 1.

[0025] Figure 5 It shows that the porous calcium carbonate prepared in Example 1 is vaterite-type calcium carbonate, and the porous calcium carbonate prepared in Example 2 contains two crystal forms of calcium carbonate, namely vaterite-type and calcite-type.

[0026] The present invention utilizes the calcium component in magnesium smelting reduction slag to prepare porous calcium carbonate, thereby alleviating the environmental and cost problems caused by processing a large amount of magnesium smelting reduction slag. It is expected that more types of calcium carbonate products with high added value can be prepared using magnesium smelting reduction slag as raw material, thereby creating higher environmental and economic benefits.

Claims

1. A method for preparing porous calcium carbonate using magnesium smelting reduction slag, characterized in that: The method comprises the following steps: a. The magnesium reduction slag having a particle size and a calcium extracting agent solution are mixed and added to the reactor, and the reactor is connected to the tail gas absorption unit; b. The magnesium smelting reduction slag reacts with the calcium extracting agent solution, and after the reaction is completed, the mixture is filtered to obtain a leaching solution rich in calcium ions; c. Take the calcium ion-rich leachate, into which carbon dioxide gas is introduced, and when the system is neutral, stop introducing carbon dioxide and ageing, and then obtain porous calcium carbonate by filtration; The components of magnesium smelting reduction slag include dicalcium silicate, magnesium oxide, and iron compounds, with their mass fractions being 70%-80%, 1%-5%, and 10%-15%, respectively. The iron compounds are calcium ferrite and ferroferric oxide.

2. The method for preparing porous calcium carbonate using magnesium smelting reduction slag according to claim 1, characterized in that: The particle size of the magnesium smelting reduction slag in step a is 100-300 meshes.

3. The method for preparing porous calcium carbonate using magnesium smelting reduction slag according to claim 1, characterized in that: The calcium extracting agent in step a is ammonium acetate or glycine.

4. The method for preparing porous calcium carbonate using magnesium smelting reduction slag according to claim 1, characterized in that: The concentration of the calcium extracting agent solution in step a is 80-400 g / L.

5. The method for preparing porous calcium carbonate using magnesium smelting reduction slag according to claim 1, characterized in that: The reaction temperature in step b is 40-100°C.

6. The method for preparing porous calcium carbonate using magnesium smelting reduction slag according to claim 1, characterized in that: The ratio of the amount of carbon dioxide introduced in step c to the amount of calcium ions in the used leaching solution is 1:1-3:

1.

7. The method for preparing porous calcium carbonate using magnesium smelting reduction slag according to claim 1, characterized in that: The reaction temperature in step c is 5-35°C.

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