CN110817878A

CN110817878A - Method for preparing calcium carbide from calcium carbide slag

Info

Publication number: CN110817878A
Application number: CN201911227212.2A
Authority: CN
Inventors: 宿新泰; 王淦; 杨超; 刘峰; 唐福文
Original assignee: Xinjiang Guofeng Jiahe Environmental Technology Co Ltd
Current assignee: Xinjiang Guofeng Jiahe Environmental Technology Co Ltd
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2020-02-21

Abstract

The invention belongs to the technical field of solid waste resource utilization, and particularly relates to a method for preparing calcium carbide by using calcium carbide slag, which comprises the following steps: (1) purifying the carbide slag; (2) preparing CaO carbon-containing pellets; (3) preparing the calcium carbide. The process provided by the invention can produce high-efficiency economic and environmental benefits.

Description

Method for preparing calcium carbide from calcium carbide slag

Technical Field

The invention belongs to the technical field of solid waste resource utilization, and particularly relates to a method for preparing calcium carbide from calcium carbide slag.

Background

At present, the calcium carbide hydrolysis-chlorination method is a main method for industrially preparing PVC. According to the production experience, 1.2 tons of carbide slag (dry basis) are generated per 1 ton of PVC, and 3276 ten thousand tons of carbide slag are generated nationwide in 2016 only. The main component of the carbide slag is Ca (OH)₂And the fertilizer has strong alkalinity (the pH value of an aqueous solution reaches 12.5), not only occupies a large amount of land, but also pollutes the environment when being directly stacked, and the development of enterprises is limited for a long time if the fertilizer is not properly treated.

Calcium carbide is one of the basic raw materials in organic synthetic chemical industry, and the industry generally adopts an electric heating method to produce the calcium carbide, namely, raw lime (CaO) and carbon-containing raw materials (coke, anthracite or petroleum coke)Synthesized in a calcium carbide furnace. The quicklime is generally derived from the pyrolysis of limestone, but limestone is a non-renewable resource after all, and the exploitation of limestone can cause certain damage to the environment. Along with the stricter and stricter national requirements on the exploitation of limestone ores, the production of quicklime by taking carbide slag as a raw material is more and more urgent and realistic. In the process of preparing calcium carbide by using quick lime as a raw material, in order to reduce energy consumption in the production process of the calcium carbide and realize the purpose of safe and efficient production, the quality of the raw material CaO needs to be strictly controlled. In which the CaO content must exceed 92%, CaCO which is not decomposed₃The content of Al is not more than 7%, and the water content is less than 1%³⁺、Fe³⁺、Mg²⁺，PO₄ ^3-Etc. with the content of impurities minimized. When calcium carbide is produced by taking quick lime as a raw material, impurities contained in the quick lime can be melted into the calcium carbide when the quick lime is melted in a calcium carbide furnace, so that the quality of the calcium carbide is reduced; meanwhile, the impurities can be gradually enriched in the carbide slag, so that the further utilization of the carbide slag is influenced, and the reduction of the impurities in the quicklime has great significance for the quality of the carbide and the utilization of the carbide slag.

Humic acid is a common chemical production raw material and has the characteristic of acid precipitation and alkali dissolution. The surface of the humic acid is rich in-COOH and-OH groups, so that the humic acid is a good metal ion adsorbent, and experiments prove that the humic acid has an obvious inhibition effect on the precipitation of phosphate under an alkaline condition. Meanwhile, humic acid is also used as a binder in industry.

Disclosure of Invention

The invention aims to provide a production process for preparing calcium carbide by using carbide slag, which is a solid waste material polluting the environment, as a raw material. The calcium carbide with high added value is obtained by comprehensively utilizing the characteristics of humic acid and adjusting the time and the temperature for operating each section, the carbide slag/humic acid ratio and the humic acid type.

The technical scheme of the invention is as follows: a method for preparing calcium carbide by using calcium carbide slag comprises the following steps:

(1) purifying the carbide slag: adding water into carbide slag, stirring and pulping to prepare slurryAdding humic acid into the slurry, and fully stirring to ensure that-COOH and-OH groups on the surface of the humic acid fully adsorb free Al in the slurry³⁺、Fe³⁺、Mg²⁺(ii) a Then carrying out suspension separation; regulating pH value of the separated solution to acidity to allow humic acid to be resolved to obtain Al³⁺、Fe³⁺、Mg²⁺Ions; dewatering and drying the separated and purified carbide slag for later use;

(2) preparing CaO carbon-containing pellets: adding humic acid into the carbide slag prepared in the step (1), uniformly mixing, then granulating, drying and calcining at 800-;

(3) preparing calcium carbide: adding humic acid into the CaO carbon-containing spheres prepared in the step (2), uniformly mixing, adding into a calcium carbide furnace for electrothermal synthesis reaction, and taking carbon elements in the humic acid as a high-temperature reducing agent to produce and obtain the high-purity calcium carbide.

The humic acid comprises humic acid extracted from weathered coal, sodium humate or humic acid treated by mixed acid, which are all commercially available.

And (3) optimizing the design, wherein the humic acid and the carbide slag slurry in the step (1) are fully stirred for 0.5 to 24 hours.

Optimizing the design, and recovering humic acid by adjusting the pH value of the humic acid-containing alkali liquor in the step (1).

And (3) optimizing the design, wherein the water content of the carbide slag dried in the step (1) is less than 15%.

And (3) optimizing the design, wherein the mass ratio of the humic acid to the carbide slag in the step (2) is 0.5-3.0.

The optimization design is carried out, in the step (2), the calcining temperature of the carbide slag is 800-.

And (4) optimizing the design, wherein the mass ratio of the humic acid to the CaO carbon-containing pellets in the step (3) is 0.5-5.0.

The optimization design, in the step (3), the temperature of the calcium carbide furnace is 1900-2200 ℃, and the time is 0.5-2 hours.

Has the advantages that: 1. the process provided by the invention can produce high-efficiency economic and environmental benefits. Preparation of high-added-value chemical industry from cheap humic acid and industrial solid waste carbide slagThe industrial calcium carbide can solve the environmental problems caused by stacking of the calcium carbide slag and the exploitation of limestone mine, change waste into valuable and generate extra economic benefit. 2. The calcium carbide synthesized by the process provided by the invention has low content of impurities, and can be used for producing high-purity PVC products. 3. The raw materials (carbide slag and humic acid) used in the process provided by the invention can be recycled and reused for many times, so that the utilization efficiency of the raw materials can be improved, the discharge of waste materials is reduced, and the influence of enterprise production on the environment is reduced. 4. The main components of humic acid are organic components containing carbon, hydrogen and oxygen and a small amount of SiO₂And metal ions, treating with mixed acid (HCl, HF) to remove SiO₂After being mixed with metal ions, the humic acid can be used as an ion adsorbent, a binder and a high-temperature reducing agent. In the purification process of the carbide slag, humic acid can be used as an ion adsorbent to separate Al from the carbide slag³⁺、Fe³⁺、Mg²⁺And phosphate impurities; in the process of preparing the CaO carbon-containing pellets, humic acid can be used as a binder and a pore-forming agent, so that the thermal strength of the CaO carbon-containing microspheres can be improved, the porosity of the carbide slag can be increased through high-temperature oxidation pore-forming, and the efficiency of decomposing the carbide slag into CaO can be improved; in the process of preparing the calcium carbide, humic acid can also be used as a carbon source to reduce CaO to obtain the calcium carbide with high added value.

Drawings

FIG. 1 is a molecular structure model diagram of humic acid; FIG. 2 is an infrared characterization analysis chart of humic acid; FIG. 3 is a process flow chart for preparing calcium carbide from calcium carbide slag.

Detailed Description

Example 1, a method for preparing calcium carbide from calcium carbide slag includes:

(1) adding 250 parts of water into 100 parts of carbide slag, uniformly mixing and screening insoluble large particles; adding 50 parts of humic acid extracted from weathered coal into the mixed slurry, mixing and stirring for 1 hour, and feeding the mixed solution into a suspension separator; regulating the pH value of the separated liquid to 5 by using HCl so as to separate out humic acid under an acidic condition; 80-85 parts of separated solid carbide slag enter a vacuum belt for dehydration and drying for later use;

(2) taking 100 parts of dehydrated and dried carbide slag, adding 200 parts of humic acid, uniformly mixing, granulating, drying, and roasting at 1000 ℃ for 1 hour in an air atmosphere to obtain high-purity CaO carbon-containing pellets for later use; high-heat tail gas during roasting can be used for drying the carbide slag and the sodium humate separated in the step (1);

(3) and mixing the prepared CaO carbon-containing pellets and humic acid according to the proportion of 1:3, uniformly mixing, feeding into an electric heating furnace for electrothermal synthesis reaction, setting the temperature of the electric heating furnace to 2100 ℃, and reacting for 2 hours to obtain the calcium carbide with high added value.

Embodiment 2, a method for preparing calcium carbide from calcium carbide slag, comprising the following steps:

(1) adding 100 parts of carbide slag into 150 parts of water, uniformly mixing, and screening insoluble large particles; adding 40 parts of sodium humate into the mixed slurry, mixing and stirring for 20 hours, and feeding the mixed solution into a suspension separator; regulating the pH value of the separated liquid to 5 by using HCl so as to separate out humic acid under an acidic condition; 80-85 parts of separated solid carbide slag are put into a vacuum belt for dehydration and drying for later use;

(2) taking 100 parts of dehydrated and dried carbide slag, adding 50 parts of sodium humate, uniformly mixing, granulating, drying, and roasting at 1000 ℃ for 0.5 hour in an air atmosphere to obtain high-purity CaO carbon-containing pellets for later use; high-heat tail gas during roasting can be used for drying the carbide slag and the sodium humate separated in the step (1);

(3) and mixing the prepared CaO carbon-containing pellets and sodium humate according to the proportion of 1:3, uniformly mixing, and then sending into an electric heating furnace for electric heating synthesis reaction, wherein the temperature of the electric heating furnace is set to 2200 ℃, and reacting for 0.5 hour to obtain the calcium carbide with high added value.

TABLE 1 analysis of the composition (mass fraction) of natural limestone and of the carbide slag purified in the examples

Table 2 elemental composition analysis of humic acid (% by mass)

And (4) conclusion: the calcium carbide synthesized by using the high-pollution calcium carbide slag and the low-cost humic acid as raw materials not only reduces the environmental pollution, but also can generate economic benefits, and is a sustainable production mode.

Claims

1. A method for preparing calcium carbide by using calcium carbide slag is characterized by comprising the following steps: the method comprises the following steps:

(1) purifying the carbide slag: adding water into carbide slag, stirring and pulping to prepare slurry, adding humic acid into the slurry, and fully stirring to ensure that-COOH and-OH groups on the surface of the humic acid fully adsorb free Al in the slurry³⁺、Fe³⁺、Mg²⁺(ii) a Then carrying out suspension separation; regulating pH value of the separated solution to acidity to allow humic acid to be resolved to obtain Al³⁺、Fe³⁺、Mg²⁺Ions; dewatering and drying the separated and purified carbide slag for later use;

(2) preparing CaO carbon-containing pellets: adding humic acid into the carbide slag prepared in the step (1), uniformly mixing, then granulating, drying and mixing at 800-^oC, calcining to obtain high-purity CaO carbon-containing pellets for later use;

2. The method for preparing calcium carbide from carbide slag as claimed in claim 1, wherein the method comprises the following steps: the humic acid comprises humic acid extracted from weathered coal, sodium humate or humic acid treated by mixed acid, and is commercially available.

3. The method for preparing calcium carbide from carbide slag as claimed in claim 1, wherein the method comprises the following steps: mixing the humic acid and the carbide slag slurry in the step (1), and then fully stirring for 0.5-24 hours.

4. The method for preparing calcium carbide from carbide slag as claimed in claim 1, wherein the method comprises the following steps: and (2) recovering humic acid by adjusting the pH value of the humic acid-containing alkali liquor in the step (1).

5. The method for preparing calcium carbide from carbide slag as claimed in claim 1, wherein the method comprises the following steps: the water content of the carbide slag dried in the step (1) is less than 15%.

6. The method for preparing calcium carbide from carbide slag as claimed in claim 1, wherein the method comprises the following steps: in the step (2), the mixing mass ratio of the humic acid to the carbide slag is 0.5-3.0.

7. The method for preparing calcium carbide from carbide slag as claimed in claim 1, wherein the method comprises the following steps: in the step (2), the calcining temperature of the carbide slag is 800-^oC, the time is 0.5-2 hours.

8. The method for preparing calcium carbide from carbide slag as claimed in claim 1, wherein the method comprises the following steps: the mass ratio of the humic acid to the CaO carbon-containing pellets in the step (3) is 0.5-5.0.

9. The method for preparing calcium carbide from carbide slag as claimed in claim 1, wherein the method comprises the following steps: in the step (3), the temperature of the calcium carbide furnace is 1900-^oC, the time is 0.5-2 hours.