Method for resource utilization of copper slag through steelmaking process platform

Abstract

The invention relates to process contents of two subjects of comprehensive resource utilization of copper slag and ferrous metallurgy process, in particular to a method for resource utilization of copper slag through a steelmaking process platform. After waste magnesia carbon bricks of a converter steel plant are subjected to process treatment, part of active materials are added and mixed with copper slag for pelletizing (the diameter of pellets is 5-50 mm), and the pellets are added into a slag tank along with steel slag flow in the slag tapping process after converter smelting is finished. According to the technology, the technological structure of the steel slag is optimized at the same time, and the economic benefits and the environmental protection benefits are huge.

Description

Technical Field

[0001] The invention relates to the process contents of two disciplines, namely, comprehensive resource utilization of copper slag and iron and steel metallurgical process, and specifically is a method for resource utilization of copper slag through a steelmaking process platform. Background Art

[0002] Copper slag is the slag containing copper, nickel and iron produced during the copper smelting process. my country's copper production is mainly based on pyrometallurgy, and pyrometallurgy produces 2 to 3 tons of copper slag for every ton of copper produced.

[0003] The amount of copper slag is large, and it contains a variety of valuable metals such as Fe, Cu, and Co. The iron-containing substances in copper slag are weakly magnetic phases, and it is difficult to recover the iron-containing materials through crushing and magnetic separation processes. Although there are many methods for the comprehensive utilization of copper slag, such as pyrometallurgical depletion, wet leaching, flotation enrichment, etc., there has never been a method that can fundamentally solve the problem of comprehensive resource utilization of copper slag. The large-scale stockpiling of copper and cobalt-containing copper slag not only causes an extreme waste of resources, but also requires a large amount of land and the risk of potential environmental pollution, which seriously hinders the sustainable development of copper smelting enterprises. The composition of copper slag from a factory in Fuyun County, Xinjiang is shown in the table below: ; MgO-C bricks are refractory materials made of magnesia (high temperature sintered magnesia or fused magnesia) and carbon materials, and various carbonaceous binders. MgO-C bricks are widely used in steel enterprises due to their high refractoriness, excellent thermal shock resistance and strong corrosion resistance, and are most widely used in converter steelmaking and electric furnace steelmaking processes.

[0004] Magnesia carbon bricks are dismantled after the furnace service life is reached in the steelmaking process. The dismantled waste magnesium carbon bricks are divided into three-layer structures: original layer, metamorphic layer, and reaction layer. Due to this structure, it is difficult to fully utilize the waste magnesium carbon bricks for high-value resource utilization. In 2015, the inventor developed a process technology for producing magnesium balls from waste magnesium carbon bricks for steelmaking, which has been applied and promoted in large-scale steel companies such as China Baowu Group. However, the potentially valuable reducing agent components of the waste magnesium carbon bricks have not been fully utilized, nor has a process method for utilizing the waste magnesium carbon bricks as reducing agents been developed. The main components of the waste magnesium carbon bricks produced by Yili Steel are shown in Table 2 below: ; Converter slag is industrial waste generated during the converter steelmaking process. The characteristic of converter liquid slag is high slag basicity. Each ton of liquid slag contains 400 to 600KWh of thermal energy. There is currently no effective process for resource utilization.

[0005] The resource utilization of converter slag is mainly concentrated in cement production, road construction, building materials, engineering backfill and other fields. However, the special properties of slag itself determine that there are some unstable factors in the resource utilization of slag. Among the process technologies to eliminate the instability of slag, the most valuable one is slag modification technology, that is, by changing the properties of slag, the process purpose of reducing f-CaO and f-MgO in slag is achieved. Summary of the invention

[0006] The purpose of the present invention is to provide a method for resource utilization of copper slag through a steelmaking process platform. After the process treatment, some active materials are added and mixed with the copper slag to form balls. During the slag discharge process at the end of converter smelting, the copper slag is added into the slag pot along with the slag flow. The physical heat and high basicity characteristics of the converter slag are utilized to reduce and recover the heavy metal elements in the copper slag for resource utilization as raw materials in the steel industry. At the same time, the process structure of the slag can be optimized, with huge economic and environmental benefits.

[0007] The process method adopted by the present invention is a method for resource utilization of copper slag through a steelmaking process platform, and the process steps of the method are as follows: 1) Crushing the discarded magnesia carbon bricks from the converter and ladle of the steel plant into 150 mesh and transporting them to the pelletizing production line for standby use; 2) The water-quenched copper slag produced by the copper plant is transported to the pelletizing production line for standby use; 3) Purchase industrial heavy oil and transport it to the pelletizing production line for use; 4) The copper slag, waste magnesia carbon bricks and industrial heavy oil are mixed evenly in a mass percentage of 65:35:10, and then pressed into 5-50 mm pellets on a dry powder pelletizing machine, and the pellets are transported to the converter production line for standby use; 5) When the converter is slag-discharging, add the above pellets along with the slag flow, adding 200-250kg pellets per ton of liquid slag; 6) After the slag pot is cooled naturally for 180 minutes, pour the steel slag in the slag pot into the slag pool or slag pit and treat it according to the hot slag pouring or hot slag stuffing process; 7) After the hot slag or hot smoldering slag process treatment, the heavy metal substances Fe, Ni, and Cu are screened and recovered by the steel slag magnetic separation production line, and are used as raw materials for steelmaking. The remaining tailings are used as raw materials for cement production and building materials.

[0008] The present invention crushes the waste magnesia carbon bricks to 150 mesh, mixes them with copper slag, adds 10% industrial heavy oil as a binder, and presses them into pellets with a diameter of 5 to 50 mm on a high-pressure dry powder pelletizing machine. When the slag is discharged at the end of the converter smelting, the pellets are added to the slag pot along with the slag flow, and the waste heat of the slag is used to reduce the copper slag and the iron compounds in the slag. At the same time, the slag-forming reaction is used to reduce the f-CaO and f-MgO in the converter slag. The treated slag is treated according to the conventional slag treatment process. The reduced iron and magnetic iron oxide in the copper slag are recycled in the slag magnetic separation production line, and the sulfur, silicon dioxide, etc. in the copper slag are converted into components of the slag and used as a resource of the slag. Since the process reduces the alkalinity of the converter slag, the stability of the resource utilization of the slag is improved, and the wear-resistant phase of the slag is reduced, which is conducive to the resource utilization of the slag.

[0009] The basic process characteristics of the present invention are as follows: 1. After the waste magnesia carbon bricks are crushed and ground, the crystal structure of the magnesia carbon bricks has a strong ability to participate in chemical reactions. After being mixed with copper slag and added to the high-temperature converter liquid steel slag, it can quickly participate in metallurgical physical and chemical reactions. The MgO in the magnesia carbon bricks reacts with the SiO2 in the copper slag to form a low-melting-point olivine phase. The antioxidant in the waste magnesia carbon bricks can be used as a reducing agent to participate in the reaction in the oxidizing steel slag to reduce the heavy metal iron, copper, nickel, etc. in the copper slag and steel slag; 2. Add industrial heavy oil as a binder and reducing agent to the pellets. The heavy oil needs to be cracked to participate in the reaction, which avoids the accident of slag overflow in the converter slag pot due to the violent reduction reaction of the reducing agent when the pellets are added to the steel slag. The chemical reaction rate is controllable, and the carbon thermal reduction reaction and roasting magnetization principle can be effectively utilized to reduce the iron-containing minerals in the copper slag to a metallic state or a low-cost strong magnetic substance, which can be separated and recycled for resource utilization through the screening and magnetic separation production line; 3. The present invention adopts the carbon thermal reduction reaction and roasting magnetization principle to utilize copper slag as a resource. The two processes are combined together. The iron element in the copper slag can be converted into metallic iron or magnetic low-valent iron oxide by using magnesia carbon bricks and reducing agents in industrial heavy oil. It can be recycled in the steel slag magnetic separation production line, which can save process costs.

[0010] The innovative points of the present invention are as follows: 1. The biggest innovation of the present invention is to utilize waste magnesia carbon bricks as alkaline reducing agents. The antioxidants AlN, SiC, graphite carbon, etc. in the waste magnesia carbon bricks react with the iron compounds in the copper slag to reduce the iron element in the copper slag to metallic iron. The iron-containing substances that have not undergone the reduction reaction are transformed by roasting magnetization through the physical heat of the steel slag, so that they are converted into steelmaking raw materials that can be recovered through the magnetic separation process, thereby realizing the resource utilization of high-value iron elements in the copper slag; 2. The inventors utilized copper slag, which is an acidic slag with low basicity, as a modifier for converter slag, thereby optimizing the process structure of slag, reducing f-CaO in converter slag, and improving the stability of slag resource utilization; 3. The inventor uses industrial heavy oil as a binder and a substance to increase the reactivity of pellets. The C and H produced after the cracking of the heavy oil react with the oxides in the copper slag and steel slag. During the escape of the generated gas, the liquid steel slag is stirred, which is beneficial to the metallurgical chemical reaction.

[0011] The present invention is a process technology developed to solve the problem of resource utilization of copper slag in copper smelters. The relevant tests of the process technology have been verified in Xinjiang Xinyuan County Zhabao Environmental Protection Technology Co., Ltd. The inventor team has solved many industry problems. Among them, the relevant content of the scientific research project "Technology for Resource Utilization of Hazardous Waste from Cooperative Electrolytic Aluminum in Steelmaking Production" has been promoted in China as a new technology for resource utilization of metallurgical solid waste. The process technology of the present invention does not contain any bad intentions. The key technology in the process content is the first application of the inventor's innovative technology in the field of steel slag treatment in the field of copper smelting. The process content is very difficult.

[0012] The beneficial contribution of the present invention is as follows: the present invention utilizes waste magnesia carbon bricks, industrial heavy oil and converter high-temperature steel slag to synergistically treat copper slag, effectively utilizing the waste heat of the steel slag, while optimizing the stability of the converter steel slag and improving the value of the resource utilization of the steel slag; copper slag is a solid waste that is difficult to utilize as a resource, and only about 50% of the copper slag is utilized as a resource in the cement industry. The present process technology can fully solve the problem of resource utilization of copper slag, with huge economic benefits and significant environmental benefits. DETAILED DESCRIPTION

[0013] The implementation process of the present invention is described by taking a copper smelter in Altay, Xinjiang and a steelmaking plant production line of Xinjiang Yili Iron and Steel Co., Ltd. as examples: A method for resource utilization of copper slag through a steelmaking process platform, the process steps of the method are as follows: 1) Crushing the discarded magnesia carbon bricks from Yigang converter and ladle into 150 mesh and transporting them to the pelletizing production line for standby use; 2) The water-quenched copper slag produced by the Fuyun County Copper Plant is transported to the pelletizing production line for standby use; 3) Purchase industrial heavy oil and transport it to the pelletizing production line for use; 4) The copper slag, waste magnesia carbon bricks and industrial heavy oil are mixed evenly in a mass percentage of 65:35:10, and then pressed into 5-50 mm pellets on a dry powder pelletizing machine, and the pellets are transported to the converter production line for standby use; 5) When the converter is slag-discharging, add the above pellets along with the slag flow, adding 200-250kg pellets per ton of liquid slag; 6) After the slag pot is cooled naturally for 180 minutes, pour the steel slag in the slag pot into the slag pool or slag pit and treat it according to the hot slag pouring or hot slag stuffing process; 7) After the hot slag or hot smoldering slag process treatment, the heavy metal substances Fe, Ni, and Cu are screened and recovered by the steel slag magnetic separation production line, and are used as raw materials for steelmaking. The remaining tailings are used as raw materials for cement production and building materials.

Claims

1. A method for resource utilization of copper slag through a steelmaking process platform, characterized in that The process steps of this method are as follows: 1) Crushing the discarded magnesia carbon bricks from the converter and ladle of the steel plant into 150 mesh and transporting them to the pelletizing production line for standby use; 2) The water-quenched copper slag produced by the copper plant is transported to the pelletizing production line for standby use; 3) Purchase industrial heavy oil and transport it to the pelletizing production line for use; 4) The copper slag, waste magnesia carbon bricks and industrial heavy oil are mixed evenly in a mass percentage of 65:35:10, and then pressed into 5-50 mm pellets on a dry powder pelletizing machine, and the pellets are transported to the converter production line for standby use; 5) When the converter is slag-discharging, add the above pellets along with the slag flow, adding 200-250kg pellets per ton of liquid slag; 6) After the slag pot is cooled naturally for 180 minutes, pour the steel slag in the slag pot into the slag pool or slag pit and treat it according to the hot slag pouring or hot slag stuffing process; 7) After the hot slag or hot smoldering slag process treatment, the heavy metal substances Fe, Ni, and Cu are screened and recovered by the steel slag magnetic separation production line, and are used as raw materials for steelmaking. The remaining tailings are used as raw materials for cement production and building materials.