All-solid waste (Dexing copper mine tailing-steel slag-fly ash) system foamed ceramic and preparation method thereof

Abstract

The invention discloses full solid waste system foamed ceramic and a preparation method thereof. The selected raw materials comprise Dexing copper mine tailings, steel slag and fly ash. The mass percent of the Dexing copper mine tailings is 53-69%, the mass percent of the steel slag is 6-8%, and the mass percent of the coal ash is 23-41%. The three raw materials are subjected to ball milling and complete drying, and are uniformly mixed with an organic binder (7wt% of a polyvinyl alcohol solution) accounting for 5% of the total mass of the raw materials in a ceramic mortar to obtain the batch. And pouring the batch into a metal mold, and carrying out compression molding on the batch under the pressure of 20MPa by using a small-sized manual sample press to obtain a foamed ceramic green body. The foamed ceramic green body is placed in a high-temperature muffle furnace for high-temperature sintering, the sintering schedule is 1180-1200 DEG C / 1 h, furnace cooling is carried out, and the foamed ceramic product is obtained. The prepared full-solid-waste-system foamed ceramic has excellent comprehensive performance, including low volume density (0.32-0.83 g / cm < 3 >), high porosity (61.64-89.12%) and high compressive strength (0.27-3.96 MPa), and has the potential of being applied to building walls and heat-insulating and fireproof materials.

Description

Technical Field

[0001] The invention relates to efficient resource utilization of Dexing copper mine tailings, steel slag and fly ash, and in particular to a method for preparing foam ceramics of a full solid waste system. Background Art

[0002] As China's largest associated gold and silver mine, Dexing Copper Mine has left a large amount of difficult-to-handle Dexing Copper Mine tailings after decades of mining. However, in the face of such a large output of tailings, the current solution is just a simple tailings pond storage. Once there is a problem with the tailings pond, the Dexing Copper Mine tailings and tailings water will have a bad impact on the surrounding ecological environment. Therefore, in order to solve the potential dangers of Dexing Copper Mine tailings, it is extremely necessary to explore ways to utilize them as resources.

[0003] Fly ash is one of the byproducts of thermal power generation. The main treatment method is also simple stockpiling, which not only occupies precious land resources, but also causes water and soil pollution, destroys the ecological balance and causes harm. At present, there are about 200 million tons of fly ash accumulated in my country every year. Adding the accumulated amount in the past, the total amount of fly ash accumulated in my country has exceeded 3 billion tons. Faced with such a large amount of fly ash, how to efficiently recycle it is a major challenge.

[0004] As the main by-product of the steelmaking process, steel slag is increasingly polluting the environment. According to statistics, my country's current annual output of steel slag reaches 120 million tons, and the cumulative reserves have exceeded 2 billion tons, which seriously encroaches on agricultural land resources and pollutes the ecological environment. Although domestic steel slag has been used in sintering ingredients, blast furnace flux, cement admixture, road construction gravel, new concrete, carbonization maintenance materials, wastewater treatment, soil conditioner and other fields, most of them are used as auxiliary ingredients, and their actual utilization rate has not reached the ideal level. The comprehensive utilization rate of steel slag is only 20-30%. Therefore, the efficient resource utilization of steel slag is urgent.

[0005] Energy conservation and emission reduction are important goals for my country's sustainable economic development. Foam ceramics, which are lightweight, high-strength, high-porosity and environmentally friendly, have excellent effects in heat insulation, thermal insulation, and sound insulation, and show great application potential in the fields of building walls and heat insulation and fireproof materials. Therefore, in recent years, foam ceramics have been widely reported, among which the preparation of foam ceramic materials using different industrial solid wastes has received great attention, and related research has also been reported in many reports.

[0006] In the study of solid waste resource utilization of copper mine tailings, steel slag and fly ash, Chinese patent application number CN202310037053.X discloses a method for preparing daily-use ceramics using copper mine tailings and a processing method. In addition to copper mine tailings, the raw materials also include kaolin, potassium feldspar, calcium-based bentonite, boron mud, magnet tailings and complex iron removers. This method has many types of raw materials, a complex heat treatment system, and a complex iron remover is added during the preparation process. The utilization rate of copper mine tailings is not high. It does not involve the preparation of materials using all solid waste as raw materials, nor does it involve the resource utilization of steel slag and fly ash.

[0007] Chinese patent application number CN202311023949.9 discloses a method for preparing high-strength sintered foam ceramics using fly ash as the main raw material. The required raw materials include titanium slag, fly ash and asbestos tailings. The preparation process of this method is relatively complicated, and the cooling and sintering process requires multiple drying treatments, and does not involve the resource utilization of copper mine tailings and steel slag.

[0008] Chinese patent application number CN202211728844.9 discloses a ceramic material with steel slag as the main component and modifier and foaming agent as auxiliary components. The steel slag utilization rate of the ceramic material prepared by this method is not high, and modifier and foaming agent need to be added. The production cost is high and the waste slag utilization rate is average. Summary of the invention

[0009] The invention provides a full solid waste system (Dexing copper mine tailings / steel slag / fly ash) foam ceramic and a preparation method thereof.

[0010] The object of the present invention is achieved in this way. A full solid waste system ceramic and a preparation method thereof, characterized in that the steps are as follows:

[0011] 1) Raw materials include: Dexing copper mine tailings, steel slag, and fly ash;

[0012] 2) After ball milling and drying, the particle sizes of the three raw materials are all above 200 mesh;

[0013] 3) Weighing the three raw materials according to the pre-designed mass ratio (Dexing copper mine tailings: 53-69%, steel slag: 6-8%, fly ash: 23-41%), and mixing them evenly with 5% of the total mass of the raw materials (7wt% polyvinyl alcohol solution) in a ceramic mortar to obtain a batch material;

[0014] 4) loading the batch material into a metal mold and pressing it at a pressure of 20 MPa using a small manual pressing machine to obtain a foam ceramic body;

[0015] 5) placing the foam ceramic body into a high-temperature muffle furnace, sintering at a temperature of 1180-1200° C. / 1 h, a heating rate of 5° C. / min, and cooling in the furnace to obtain foam ceramic.

[0016] In the present invention, SiO2 and Al2O3 in the chemical composition of the three raw materials can construct the skeleton structure of the foam ceramic. Alkali / alkaline earth metal oxides (such as CaO, Na2O) can be used as sintering aids to reduce the sintering temperature, and react with SiO2 and Al2O3 to generate silicates, aluminates, and aluminosilicates, and then form a glass phase. Other chemical compositions (such as Fe2O3) can be used as foaming compositions to provide conditions for the formation of the porous structure of the foam ceramic. The solid waste introduction amount of the prepared foam ceramic reaches 100%, which belongs to the environmentally friendly foam ceramic material of the full solid waste system. The process is simple, the cost is low, and it has the characteristics of high porosity, high compressive strength, etc., and it has application potential in building walls and thermal insulation and fireproof materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a physical picture of the foam ceramic prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0018] The present invention is further described below with reference to the embodiments, but the protection scope of the present invention should not be limited thereto.

[0019] A full solid waste system foam ceramic and a preparation method thereof, the steps of which are as follows:

[0020] 1) Raw materials include: Dexing copper mine tailings, steel slag, and fly ash;

[0021] 2) After ball milling and drying, the particle sizes of the three raw materials are all above 200 mesh;

[0022] 3) Weigh the three raw materials according to the pre-designed mass ratio (Dexing copper mine tailings: 53-69%, steel slag: 6-8%, fly ash: 23-41%), and mix them evenly with 5% of the total mass of the raw materials (7wt% polyvinyl alcohol solution) in a ceramic mortar to obtain a batch material. The organic binder is decomposed during the later high-temperature sintering process to ensure that the raw materials of the foam ceramics are all from industrial solid waste;

[0023] 4) loading the batch material into a metal mold and pressing it at a pressure of 20 MPa using a small manual pressing machine to obtain a foam ceramic body;

[0024] 5) placing the foam ceramic body into a high-temperature muffle furnace, sintering at a temperature of 1180-1200° C. / 1 h, a heating rate of 5° C. / min, and cooling in the furnace to obtain foam ceramic.

[0025] Example 1

[0026] After the raw materials are ball-milled and dried, the three raw materials are weighed according to the pre-designed mass ratio (Dexing copper mine tailings: 69%, steel slag: 8%, fly ash: 23%), and mixed evenly with 5% of the total mass of the raw materials in a ceramic mortar to obtain a batch material. The batch material is then placed in a metal mold and pressed at a pressure of 20MPa in a small manual press to obtain a foam ceramic body. The foam ceramic body is then placed in a high-temperature muffle furnace and heated to 1180°C at a heating rate of 5°C / min and kept warm for 1h. After cooling in the furnace, foam ceramics are obtained, and their volume density is: 0.83g / cm 3 , porosity: 61.64%, compressive strength: 2.71MPa.

[0027] Example 2

[0028] After the raw materials are ball-milled and dried, the three raw materials are weighed according to the pre-designed mass ratio (Dexing copper mine tailings: 64%, steel slag: 7%, fly ash: 29%), and mixed evenly with 5% of the total mass of the raw materials in a ceramic mortar to obtain a batch material. The batch material is then placed in a metal mold and pressed at a pressure of 20MPa in a small manual press to obtain a foam ceramic body. The foam ceramic body is then placed in a high-temperature muffle furnace and heated to 1180°C at a heating rate of 5°C / min and kept warm for 1h. After cooling in the furnace, foam ceramics are obtained, and their volume density is: 0.36g / cm 3 , porosity: 79.63%, compressive strength: 1.09MPa (see Figure 1 ).

[0029] Example 3

[0030] After ball milling and drying, weigh the three raw materials according to the pre-designed mass ratio (Dexing copper mine tailings: 60%, steel slag: 7%, fly ash: 33%), and mix them evenly with 5% of the total mass of the raw materials in a ceramic mortar to obtain a batch material. Then put the batch material into a metal mold and press it with a pressure of 20MPa in a small manual press to obtain a foam ceramic body. Then place the foam ceramic body in a high-temperature muffle furnace and heat it to 1180℃ at a heating rate of 5℃ / min and keep it warm for 1h. After cooling in the furnace, foam ceramics are obtained, and its volume density is: 0.34g / cm 3 , porosity: 82.21%, compressive strength: 0.84MPa.

[0031] Example 4

[0032] After the raw materials are ball-milled and dried, the three raw materials are weighed according to the pre-designed mass ratio (Dexing copper mine tailings: 56%, steel slag: 6%, fly ash: 38%), and mixed evenly with 5% of the total mass of the raw materials in a ceramic mortar to obtain a batch material. The batch material is then placed in a metal mold and pressed at a pressure of 20MPa in a small manual press to obtain a foam ceramic body. The foam ceramic body is then placed in a high-temperature muffle furnace and heated to 1180°C at a heating rate of 5°C / min and kept warm for 1h. After cooling in the furnace, foam ceramics are obtained, and their volume density is: 0.57g / cm 3 , porosity: 80.45%, compressive strength: 3.77MPa.

[0033] Example 5

[0034] After ball milling and drying, weigh the three raw materials according to the pre-designed mass ratio (Dexing copper mine tailings: 53%, steel slag: 6%, fly ash: 41%), and mix them evenly with 5% of the total mass of the raw materials in a ceramic mortar to obtain a batch material. Then put the batch material into a metal mold and press it with a pressure of 20MPa in a small manual press to obtain a foam ceramic body. Then place the foam ceramic body in a high-temperature muffle furnace and heat it to 1180℃ at a heating rate of 5℃ / min and keep it warm for 1h. After cooling in the furnace, foam ceramics are obtained, and its volume density is: 0.76g / cm 3 , porosity: 68.20%, compressive strength: 3.96MPa.

[0035] Example 6

[0036] After the raw materials are ball-milled and dried, the three raw materials are weighed according to the pre-designed mass ratio (Dexing copper mine tailings: 56%, steel slag: 6%, fly ash: 38%), and mixed evenly with 5% of the total mass of the raw materials in a ceramic mortar to obtain a batch material. The batch material is then placed in a metal mold and pressed at a pressure of 20MPa in a small manual press to obtain a foam ceramic body. The foam ceramic body is then placed in a high-temperature muffle furnace and heated to 1200°C at a heating rate of 5°C / min and kept warm for 1h. After cooling in the furnace, foam ceramics are obtained, and their volume density is: 0.33g / cm 3 , porosity: 89.12%, compressive strength: 0.27MPa.

[0037] Example 7

[0038] After the raw materials are ball-milled and dried, the three raw materials are weighed according to the pre-designed mass ratio (Dexing copper mine tailings: 56%, steel slag: 6%, fly ash: 41%), and mixed evenly with 5% of the total mass of the raw materials in a ceramic mortar to obtain a batch material. The batch material is then placed in a metal mold and pressed at a pressure of 20MPa in a small manual press to obtain a foam ceramic body. The foam ceramic body is then placed in a high-temperature muffle furnace and heated to 1200°C at a heating rate of 5°C / min and kept warm for 1h. After cooling in the furnace, foam ceramics are obtained, and their volume density is: 0.32g / cm 3 , porosity: 86.29%, compressive strength: 1.17MPa.

[0039] The block density in all examples is measured according to GB / T 3810.3-2006 “Test methods for ceramic tiles Part 3 Determination of water absorption, apparent porosity, apparent relative density and bulk density”.

[0040] The porosity in all examples is measured according to GB / T 5071-2013 “Test method for true density of refractory materials”.

[0041] The flexural strength of the samples in all the examples was measured according to GB / T 1965-1996 “Test method for flexural strength of porous ceramics”.

[0042] Table 1 Performance parameters of the permeable bricks prepared in Examples 1-7

[0043]

[0044] The method for preparing high-performance environmentally friendly foam ceramics from the Dexing copper mine tailings / steel slag / fly ash system of the present invention also includes the following preferred solutions:

[0045] In a preferred embodiment, the ideal sintering temperature of the foam ceramic is 1180-1200°C / 1h.

[0046] In the preferred solution, the addition of organic binder enables the raw material particles to have a certain bonding force, which is conducive to compression molding. In addition, the binder is decomposed during the later high-temperature sintering process, ensuring that the solid waste introduction amount of the foam ceramic reaches 100%.

[0047] In summary, the technical advantages of the present invention bring particularly excellent technical effects:

[0048] 1) Successfully obtain foam ceramic products from a full solid waste system.

[0049] 2) The preparation process is simple and the cost is low.

[0050] 3) The prepared foam ceramics have excellent comprehensive performance, which is specifically reflected in the volume density of 0.32-0.83g / cm 3The porosity is 61.64-89.12%, and the compression strength is 0.27-3.96MPa. It has application potential in the fields of building walls and thermal insulation and fireproof materials.

Claims

1. A full solid waste system foam ceramic and a preparation method thereof, characterized in that: The steps are as follows: 1) The particle size range of the selected raw materials is above 200 mesh; 2) After the three raw materials are ball-milled and dried completely, they are mixed evenly with an organic binder accounting for 5% of the total weight of the raw materials in a ceramic mortar according to a pre-designed mass ratio (53-69% of Dexing copper mine tailings, 6-8% of steel slag, and 23-41% of fly ash) to obtain a batch material; 3) loading the batch material into a metal mold, and pressing the batch material into a foam ceramic body using a small manual press at a pressure of 20 MPa; 4) placing the foam ceramic body into a high-temperature muffle furnace for high-temperature sintering at a temperature range of 1180-1200° C., keeping the temperature for 1 hour, and cooling along with the furnace to obtain foam ceramic.

2. The all-solid waste system foam ceramic according to claim 1, characterized in that: The particle size of the raw materials is all above 200 meshes.

3. The all-solid waste system foam ceramic according to claim 2, characterized in that: The organic binder is a 7 wt % polyvinyl alcohol (PVA) solution.

4. The all-solid waste system foam ceramic according to claim 1, characterized in that: The solid waste utilization rate is 100%.

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