Gold tailings unburned ceramsite and preparation method thereof

Abstract

The present invention belongs to the technical field of ceramsite preparation, and specifically relates to a gold tailings unfired ceramsite and a preparation method thereof. The preparation method comprises the following steps: mixing gold tailings with industrial waste slag and grinding the mixture to obtain a powder; uniformly mixing an alkali activator, a foaming material and water to obtain a mixed solution; adding the powder and the mixed solution to a disc granulator for granulation to obtain pre-cured ceramsite; covering the surface of the pre-cured ceramsite with a film, naturally curing it at room temperature for 12 to 48 hours, and then mineralizing and curing it in the presence of carbon dioxide for 3 to 7 days to obtain the ceramsite. The preparation method can be carried out at room temperature and pressure, and the obtained gold tailings unfired ceramsite has the advantages of high carbon fixation and low energy consumption, realizing the coordinated disposal of comprehensive utilization of gold tailings and storage and utilization of carbon dioxide.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramsite preparation, and particularly relates to a gold tailings unburned ceramsite and a preparation method thereof. Background Art

[0002] Gold tailings are solid waste discharged after the gold or other useful components are recovered through the gold extraction process. They are generally alkaline and contain over 80% inorganic minerals such as silicon and aluminum oxides. Ceramic aggregate is a man-made lightweight aggregate that offers excellent properties such as lightness, high strength, thermal insulation, frost resistance, and impermeability. Its raw materials are similar in composition to gold tailings. Using gold tailings as the primary raw material, along with other auxiliary materials, and then mixing and pelletizing them, ceramsite can open up new avenues for the high-value utilization of gold tailings.

[0003] Due to the low activity of gold tailings, the production of ceramsite from gold tailings often requires high-temperature sintering or autoclaving / steam curing. For example, CN202210512855.7 discloses a method for producing lightweight ceramsite from gold tailings, cement, quicklime, and other materials through autoclaving and curing; CN201110293978.8 discloses a method for producing ceramsite from gold tailings and pulverized coal through sintering. This additional energy consumption not only increases the cost of producing ceramsite from gold tailings, but also goes against the original intention of solid waste disposal, which is to conserve energy and protect the environment. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a gold tailings unfired ceramsite and a preparation method thereof. The preparation method first prepares pre-cured ceramsite from specific raw materials containing gold tailings, and then subjects the pre-cured ceramsite to film curing and mineralization curing for a specific period of time. The obtained gold tailings unfired ceramsite has the advantages of high carbon fixation and low energy consumption, thereby realizing the coordinated disposal of comprehensive utilization of gold tailings and storage and utilization of carbon dioxide.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] A method for preparing unburned ceramsite from gold tailings comprises the following steps:

[0007] (1) mixing gold tailings with industrial waste residue and grinding them to obtain powder;

[0008] (2) uniformly mixing the alkali activator, the foaming material and water to obtain a mixed solution;

[0009] (3) adding the powder and the mixed liquid into a disc granulator for granulation to obtain pre-cured ceramsite;

[0010] (4) Before the curing, the surface of the ceramsite is covered with a film (such as a plastic wrap or a plastic film), and naturally cured at room temperature for 12 to 48 hours, and then mineralized and cured for 3 to 7 days in the presence of carbon dioxide to obtain the gold tailings unfired ceramsite.

[0011] The present invention utilizes the alkaline activity of gold tailings and industrial waste slag to achieve the preparation of unfired ceramsite with a large amount of gold tailings, thereby avoiding high-temperature sintering or autoclaving / steam curing; the bubbles formed by the foaming material can not only reduce the dead weight of the ceramsite, but also facilitate the penetration and reaction of carbon dioxide into the interior of the ceramsite during mineralization curing, thereby reducing the temperature, pressure and other conditions required for the mineralization reaction, and realizing the mineralization curing of the ceramsite at normal temperature and pressure; by adjusting the curing system, that is, the ratio of the duration of film curing and mineralization curing, the penetration capacity of carbon dioxide into the ceramsite is further improved, and the mineralization reaction of the product excited by carbon dioxide and alkali is utilized, which can not only absorb carbon dioxide, but also accelerate the strength growth of the ceramsite and reduce the curing time.

[0012] Preferably, the gold tailings comprise 80-90 parts, the industrial waste slag comprises 10-20 parts, the alkaline activator comprises 1-10 parts, the foaming material comprises 2-6 parts, and the water comprises 30-45 parts. With these proportions, the raw material components complement each other, resulting in a higher carbon fixation capacity and lower curing requirements for the ceramsite after the mineralization reaction.

[0013] Preferably, the SiO2 content in the gold tailings is ≥50wt%, more preferably ≥65wt%. Experiments have found that the higher the SiO2 content, the higher the alkaline activity of the gold tailings, which is more conducive to the hardening of ceramsite into balls.

[0014] Preferably, the industrial waste slag is selected from one or more of mineral powder, silica fume, and metakaolin; more preferably, it is mineral powder with a 28d activity index ≥ 85%. Experiments have found that using mineral powder in the above activity range as industrial waste slag is more conducive to improving the strength of ceramsite.

[0015] Preferably, the particle size of the powder is less than 200 mesh.

[0016] Preferably, the alkaline activator is selected from one or more of sodium hydroxide, potassium hydroxide, potassium silicate, and sodium silicate; more preferably, it is a mixture of sodium silicate and sodium hydroxide in a mass ratio of 1:0.8 to 1.2. Experiments have found that the use of the above-mentioned composite alkaline activator of sodium silicate and sodium hydroxide can accelerate the dissolution of aluminates and silicates in gold tailings and industrial waste slag, and improve the early strength of ceramsite.

[0017] Preferably, the foaming agent is selected from one or more of sodium dodecylbenzenesulfonate, hydrogen peroxide, aluminum powder, and ammonium bicarbonate; more preferably, sodium dodecylbenzenesulfonate. Experiments have found that sodium dodecylbenzenesulfonate is particularly suitable as a foaming agent in the system of the present invention, with mild foaming and uniform pores.

[0018] Preferably, the particle size of the ceramsite before curing is 2.36 to 26.5 mm. Experiments have found that using ceramsite in the above particle size range for subsequent film curing, especially mineralization curing, has a better effect on increasing the carbon fixation capacity of the ceramsite.

[0019] Preferably, the conditions for the mineralization curing are: a carbon dioxide concentration of more than 20 wt% and a relative humidity of more than 50%; more preferably, the mineralization curing is carried out at room temperature and pressure. Through the technical solution of the present invention, the mineralization curing of ceramsite at room temperature and pressure can be achieved with low energy consumption.

[0020] The present invention also provides a gold tailings unfired ceramsite, which is prepared by the above-mentioned preparation method.

[0021] The beneficial effects achieved by the present invention are:

[0022] The gold tailings unfired ceramsite and preparation method proposed in the present invention can be prepared at room temperature and pressure. The obtained gold tailings unfired ceramsite has the advantages of high carbon fixation and low energy consumption. Not only does it not require the additional energy consumption of high-temperature sintering or autoclaving / steam curing, but the ceramsite can also be used to absorb carbon dioxide, realizing the coordinated disposal of comprehensive utilization of gold tailings and storage and utilization of carbon dioxide. DETAILED DESCRIPTION

[0023] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or the product instructions were used.

[0024] In the following examples, all instruments used without manufacturer indication are conventional products that can be purchased through regular channels. The methods described are conventional methods unless otherwise specified, and the raw materials described are commercially available unless otherwise specified.

[0025] Example 1

[0026] Example 1 provides a gold tailings unfired ceramsite and a preparation method thereof, the raw material composition being: 80 parts of gold tailings (SiO2 content is about 65%), 20 parts of mineral powder (28d activity index is 90%), 3 parts of composite alkali activator (sodium silicate: sodium hydroxide = 1:1), 3 parts of sodium dodecylbenzene sulfonate, and 40 parts of water.

[0027] The preparation method is specifically as follows:

[0028] (1) Mix the gold tailings and industrial waste slag evenly into powder (below 200 mesh),

[0029] (2) mixing the alkali activator, the foaming material and water to form a solution;

[0030] (3) Stir part of the powder and solution for about 2 minutes and then feed it into a disc granulator. Add the remaining powder and solution while rotating until the ceramsite particle size reaches the required 9.5 mm to obtain the ceramsite before curing;

[0031] (3) After covering the pre-cured ceramsite with a layer of plastic wrap, the ceramsite is first cured at room temperature for 24 hours, and then transferred to mineralization curing for 6 days to obtain the gold tailings unburned ceramsite. The mineralization curing conditions are 40% carbon dioxide concentration and 80% relative humidity at room temperature and pressure.

[0032] Example 2

[0033] Example 2 provides a gold tailings unfired ceramsite and a preparation method thereof, the raw material composition being: 80 parts of gold tailings (SiO2 content is approximately 50%), 20 parts of mineral powder (activity index is 90%), 3 parts of composite alkali activator (sodium silicate: sodium hydroxide = 1:1), 3 parts of sodium dodecylbenzenesulfonate, and 40 parts of water.

[0034] The preparation method is the same as that of Example 1.

[0035] Example 3

[0036] Example 3 provides a gold tailings unfired ceramsite and a preparation method thereof, wherein the raw materials are composed of: 80 parts of gold tailings (SiO2 content is about 50%), 20 parts of metakaolin, 3 parts of potassium silicate, 3 parts of hydrogen peroxide, and 40 parts of water.

[0037] The preparation method is the same as that of Example 1.

[0038] Comparative Example 1

[0039] Comparative Example 1 provides a gold tailings unfired ceramsite and a preparation method thereof, the raw material composition being: 80 parts of gold tailings (SiO2 content is approximately 65%), 20 parts of mineral powder (activity index is 90%), 3 parts of composite alkali activator (sodium silicate: sodium hydroxide = 1:1), 3 parts of sodium dodecylbenzenesulfonate, and 40 parts of water.

[0040] The preparation method is the same as that of Example 1, except that in step (3), the ceramsite before curing is coated and then cured at room temperature for only 7 days.

[0041] Comparative Example 2

[0042] Comparative Example 2 provides a gold tailings unfired ceramsite and a preparation method thereof, the raw material composition being: 80 parts of gold tailings (SiO2 content is about 65%), 20 parts of mineral powder (activity index is 90%), 3 parts of composite alkali activator (sodium silicate: sodium hydroxide = 1:1), and 40 parts of water.

[0043] The preparation method is the same as that in Example 1, except that the foaming material sodium dodecylbenzenesulfonate is not added in step (2).

[0044] Test results

[0045] The ceramsite was tested for its cylinder compressive strength and bulk density 28 days after molding according to GB / T 17431.2, "Lightweight aggregates and their test methods - Part 2: Test methods for lightweight aggregates." The carbon retention rate was determined using a TG-DSC curve. The test results for the ceramsite properties are shown in Table 1.

[0046] As shown in Examples 1-3, the unfired ceramsite prepared by the present invention can achieve high-value utilization of gold tailings in large quantities and sequester some carbon dioxide, showing promising application prospects. Compared with Example 1, the ceramsite in Comparative Example 1, which was cured only by film coating after molding without carbon dioxide mineralization, showed slower strength growth. Comparative Example 2, which did not add a foaming material, showed some improvement in ceramsite strength, but significantly increased its bulk density, reduced carbon dioxide permeability, and significantly decreased its carbon sequestration rate.

[0047] Table 1

[0048] serial number Cylinder pressure strength (MPa) <![CDATA[Bulk density (kg / m 3 )]]> Carbon fixation rate (%) Example 1 7.3 850 8.1 Example 2 6.6 920 7.2 Example 3 6.1 980 6.4 Comparative Example 1 4.5 1000 0.1 Comparative Example 2 8.1 1200 1.5

[0049] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for preparing unburned ceramsite from gold tailings, characterized in that: The following steps are involved: (1) Mixing gold tailings with industrial waste residue and grinding them to obtain powder; (2) uniformly mixing the alkali activator, the foaming material and water to obtain a mixed solution; (3) adding the powder and the mixed liquid into a disc granulator for granulation to obtain ceramsite before curing; (4) before the curing, the surface of the ceramsite is covered with a film, naturally cured at room temperature for 12 to 48 hours, and then mineralized and cured in the presence of carbon dioxide for 3 to 7 days to obtain the gold tailings unburned ceramsite; The mineralization curing is carried out at normal temperature and pressure; The SiO2 content in the gold tailings is ≥50wt%; The industrial waste residue is selected from one or more of mineral powder, silica fume and metakaolin.

2. The preparation method according to claim 1, characterized in that In parts by mass, the gold tailings account for 80 to 90 parts, the industrial waste slag accounts for 10 to 20 parts, the alkali activator accounts for 1 to 10 parts, the foaming material accounts for 2 to 6 parts, and the water accounts for 30 to 45 parts.

3. The preparation method according to claim 1 or 2, characterized in that The SiO2 content in the gold tailings is ≥65wt%.

4. The preparation method according to claim 3, characterized in that The industrial waste slag is mineral powder with an activity index of ≥85%.

5. The preparation method according to claim 4, characterized in that The particle size of the powder is below 200 meshes.

6. The preparation method according to claim 5, characterized in that The alkaline activator is selected from one or more of sodium hydroxide, potassium hydroxide, potassium silicate and sodium silicate.

7. The preparation method according to claim 6, characterized in that The alkaline activator is a mixture of sodium silicate and sodium hydroxide in a mass ratio of 1:0.8-1.

2.

8. The preparation method according to claim 7, characterized in that The foaming material is selected from one or more of sodium dodecylbenzene sulfonate, hydrogen peroxide, aluminum powder, and ammonium bicarbonate.

9. The preparation method according to claim 8, characterized in that The foaming material is sodium dodecylbenzenesulfonate.

10. The preparation method according to claim 9, characterized in that The particle size of ceramsite before curing is 2.36~26.5 mm.

11. The preparation method according to claim 10, characterized in that: The conditions for the mineralization curing are: a carbon dioxide concentration of 20 wt% or more and a relative humidity of 50% or more.

12. A gold tailings unfired ceramsite, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 11.