A method of calcining cement raw meal in a methane atmosphere and co-producing a carbon material

Abstract

The application discloses a method for calcining cement raw materials in a methane atmosphere and co-producing carbon materials. The method comprises the following steps: mixing cement raw materials with solid waste in a reactor under a methane atmosphere, and calcining to obtain cement clinker, carbon monoxide, hydrogen and solid carbon materials; the solid waste is selected from at least one of the following: blast furnace slag, high-iron fly ash, steel slag, stainless steel slag, iron oxide scale and red mud. The method effectively reduces carbon emissions in the cement production process, and simultaneously produces synthesis gas and carbon materials, greatly improving the economic efficiency and environmental benefits of the process. In addition, the catalyst can come from by-products of the steel and aluminum smelting industry, realizing waste resource utilization. The technology provides a new way for the green and low-carbon transformation of the cement industry.

Description

Technical Field

[0001] This application relates to a method for calcining cement raw materials and co-producing carbon materials in a methane atmosphere, which belongs to the field of chemical engineering. Background Technology

[0002] During cement production, the calcination of limestone (mainly calcium carbonate) releases a large amount of carbon dioxide, becoming one of the major sources of global greenhouse gas emissions. To address the carbon reduction challenges in the cement industry, various technological solutions have been proposed in recent years, including the use of alternative fuels and carbon capture and storage (CFS). However, these technologies still face problems such as low energy efficiency and high cost in practical applications. Meanwhile, with the acceleration of industrial development, syngas (mainly composed of carbon monoxide and hydrogen) has broad application prospects in the chemical and energy fields, and the demand for carbon materials, as an important basic material in emerging technologies such as energy storage and catalysis, is also growing rapidly. Therefore, developing a technology that can co-produce syngas and carbon materials during cement production will greatly improve the overall economic and environmental benefits of the process. Summary of the Invention

[0003] The purpose of this invention is to provide a method for calcining cement raw materials and co-producing carbon materials in a methane atmosphere using solid waste from the metallurgical industry as a catalyst. By catalyzing the reaction of calcium carbonate with methane and methane cracking, the method reduces process carbon emissions from calcium carbonate decomposition in cement production and co-produces syngas and carbon materials.

[0004] According to one aspect of this application, a method for calcining cement raw materials and co-producing carbon materials in a methane atmosphere is provided, comprising the following steps:

[0005] In a reactor under a methane atmosphere, cement raw materials and solid waste are mixed and calcined to obtain cement clinker, carbon monoxide, hydrogen and solid carbon materials.

[0006] The solid waste is selected from at least one of blast furnace slag, high-speed iron fly ash, steel slag, stainless steel slag, iron oxide scale, and red mud.

[0007] The pressure of the methane is 0.1–0.5 MPa.

[0008] The calcination temperature is 600–1000℃.

[0009] Optionally, the calcination temperature is 800–950°C.

[0010] The solid waste is activated;

[0011] The activation temperature is 600–1000°C.

[0012] The mass ratio of cement raw materials to solid waste is 1:0.05 to 0.5.

[0013] Specifically, in a methane atmosphere, cement raw materials containing iron solid waste catalysts are calcined, causing calcium carbonate (CaCO) to react in a reducing atmosphere. At the same time, some calcium carbonate decomposes to produce carbon dioxide (CO). The carbon dioxide reacts with methane (CH) under the action of an iron-based catalyst to produce carbon monoxide (CO) and hydrogen (H), forming syngas.

[0014] The solid reaction products of the reaction process are calcium oxide (CaO) and elemental carbon. After preliminary separation of elemental carbon, the remaining calcium oxide and the iron, aluminum and silicon in the catalyst can be further calcined in a rotary kiln to obtain cement clinker.

[0015] Since iron and aluminum are essential raw materials for cement, the catalyst and calcium oxide do not need to be separated in the process, and cement clinker can be directly prepared.

[0016] The catalyst contains iron and aluminum, which enable the high-temperature pyrolysis of methane to produce hydrogen and elemental carbon (C). The conversion rate of methane can reach over 80%.

[0017] The separation step can be performed using methods such as cyclone separation.

[0018] This process achieves the co-production of cement, carbon materials and syngas during the calcination of cement clinker, and reduces the carbon emissions problem of the single calcination step in traditional processes.

[0019] This invention addresses the high carbon emissions problem in the cement industry, focusing on resolving the process emissions from calcium carbonate decomposition, which are difficult to address in current carbon reduction technologies. It is low-carbon and environmentally friendly. Simultaneously, it utilizes solid waste from the metallurgical industry, coupling cement production with carbon materials and chemical production processes to achieve low-carbon, high-efficiency, and integrated process reengineering. Compared to traditional cement production processes, the advantages of this invention are as follows:

[0020] (1) Carbon emission reduction: Compared with traditional cement production methods, this invention effectively reduces the direct emission of carbon dioxide and realizes the utilization of carbon dioxide through the introduction of methane and catalytic reaction.

[0021] (2) Co-production benefits: This method not only produces cement clinker, but also obtains carbon materials and syngas at the same time, which greatly improves the economic benefits of the overall process.

[0022] (3) Resource recycling: The iron-based catalyst used in this invention can be derived from waste materials in the iron and steel and metallurgical industries, realizing the resource utilization of waste and further improving the environmental friendliness of the process. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the production process of the present invention.

[0024] Figure 2 This is an XRD pattern of the reaction products after preliminary separation according to the present invention. Detailed Implementation

[0025] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0026] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0027] Example 1

[0028] A 50% methane-rich gas was introduced into a fluidized bed reactor, blown in from the bottom at a flow rate of 180 m³ / h. The catalyst, calcined and activated red mud powder, was mixed with cement raw materials at a 1:1 ratio and fed from the top at a flow rate of 100 kg / h. The reactor was then fully fluidized. The reactor was heated to 800°C and pressure 0.2 MPa. At this temperature, calcium carbonate in the cement raw materials underwent a series of catalytic reactions with methane, producing syngas, calcium oxide, and solid carbon. The methane conversion rate was approximately 50%, allowing for an annual production of approximately 350 tons of cement clinker, with solid carbon materials as a byproduct.

[0029] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for calcining cement raw materials and co-producing carbon materials in a methane atmosphere, characterized in that, Includes the following steps: In a reactor under a methane atmosphere, cement raw materials and solid waste are mixed and calcined to obtain cement clinker, carbon monoxide, hydrogen and solid carbon materials. The solid waste is selected from at least one of blast furnace slag, high-speed iron fly ash, steel slag, stainless steel slag, iron oxide scale, and red mud.

2. The method according to claim 1, characterized in that, The pressure of the methane is 0.1–0.5 MPa.

3. The method according to claim 1, characterized in that, The calcination temperature is 600–1000℃.

4. The method according to claim 1, characterized in that, The calcination temperature is 800–950°C.

5. The method according to claim 1, characterized in that, The solid waste is activated; The activation temperature is 600–1000°C.

6. The method according to claim 1, characterized in that, The mass ratio of cement raw materials to solid waste is 1:0.05 to 0.5.

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