Method for on-line iron extraction from converter slag

Abstract

The present application aims at the problems existing in the prior art of converter steel slag iron extraction technology, and provides an online converter steel slag iron extraction method, which comprises the following steps: 1) converting the converter steel slag in a high-temperature liquid state into a steel slag tank at one time, stirring the liquid steel slag, and adding a slag-iron separation agent to make the slag-iron separation agent fully mixed with the liquid steel slag; 2) after stirring for an appropriate time, stopping the stirring, moving out the steel slag tank, and cooling the steel slag tank; and 3) after the material in the steel slag tank is cooled, turning over the steel slag tank to pour out the steel slag, and naturally separating the slag and the iron. The method can realize online and convenient treatment of high-temperature converter steel slag in the slag tank, fully utilize the sensible heat of the molten converter steel slag, and does not need additional heat supply, so that the effect of iron recovery is achieved, the recovery rate of the obtained iron and the coarse alloy product of the iron oxide is high, the separation effect is good, and the resource recovery and utilization in the converter steel slag is maximally realized.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and particularly relates to an online method for iron extraction from converter steel slag. Background Technology

[0002] Converter slag refers to the slag formed during converter steelmaking through a reduction reaction of impurities in the ore and oxides in the furnace charge. The main chemical components of converter slag include TFe (elemental iron, FeO + Fe2O3), MgO (magnesium oxide), Al2O3 (aluminum oxide), CaO (calcium oxide), and SiO2 (silicon dioxide).

[0003] Due to its high alkalinity, high free calcium oxide content, poor grindability, and poor cementitious activity, coupled with a total iron content of 20%–30%, converter slag has long been hindered from being promoted as a resource-based product. Furthermore, without special treatment, it cannot be used as a cementitious material like blast furnace slag. Currently, the utilization rate of converter slag is low, with most of it being dumped as waste, occupying significant land resources and polluting the environment. The unutilized iron content in converter slag also represents a waste of resources, and the enormous heat energy generated during its production (up to 1600℃) remains untapped.

[0004] Existing technologies for treating converter steel slag include hot quenching, hot pouring, drum quenching, and air quenching. Hot quenching is one of the main methods. After hot quenching, the slag is crushed, screened, and magnetically separated to extract metallic iron particles and iron concentrate. The remaining slag tailings have good stability and a certain degree of activity, making them suitable for use in building materials. However, this method consumes a large amount of water, and the residual heat in the slag is not well recovered. Furthermore, because the iron in the slag exists primarily in the form of ferric oxide and ferrous oxide, which are non-magnetic, the iron recovery rate is low. With advancements in machinery and equipment, especially Chinese patents ZL 202520538892.4 (disclosed as a liquid steel slag treatment device) and ZL 202420743241.4 (disclosed as a easily movable smelting stirring and blowing equipment), the application of online reducing agent iron extraction from steel slag can significantly improve the iron recovery rate. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in current converter slag iron extraction technology by providing an online iron extraction method for converter slag. This method enables convenient online processing of high-temperature converter slag within the slag pot, fully utilizing the sensible heat of the molten converter slag without requiring additional heat input, achieving the effect of "iron recovery." The resulting crude alloy products of iron and iron oxides have high recovery rates, good separation effects, and are convenient for subsequent sorting, thus maximizing the recycling of resources from converter slag.

[0006] The technical solution of the present invention is a method for online iron extraction from converter steel slag, comprising the following steps: 1) The high-temperature liquid converter slag is transferred into a slag hopper in one go. The center and sides of the liquid slag are stirred. At the same time, a slag-iron separator is quickly added to the center and sides of the liquid slag to ensure that the slag-iron separator is fully mixed with the liquid slag. The composition of the slag-iron separator is: fluorite 3~5%, silica 38~43%, Al2O3 powder 5~7%, and carbon powder 47~52%. 2) After stirring for an appropriate time, stop stirring, remove the slag pot, and cool it. Because the density of composite converter slag is 2.7-3.0 g / cm³, the density of liquid FeO molten slag is 4.3-4.5 g / cm³, and the density of liquid pure iron is about 7.0 g / cm³, during the stirring process, the waste slag gradually floats to the top layer of the slag pot, the iron oxide gradually floats to the middle layer of the slag pot, and the iron gradually sinks to the bottom layer of the slag pot. During the cooling process, the waste slag, iron oxide, and iron solidify in layers from top to bottom in the slag pot. 3) After the material in the slag container has cooled down, invert the container to pour out the slag. The slag and iron will naturally separate, and iron and iron oxides can be obtained.

[0007] Furthermore, in the above-mentioned method for direct online iron extraction from converter slag, the slag treatment device used is the device disclosed in Chinese patents ZL 202520538892.4 or ZL202420743241.4.

[0008] Furthermore, in the above-mentioned method for direct online iron extraction from converter slag, in step 1), a layer of anti-sticking agent is laid at the bottom of the slag hopper before the slag is poured in.

[0009] Furthermore, in the above-mentioned method for direct online iron extraction from converter steel slag, in step 1), 5-20 kg of slag-iron separation agent is added per ton of steel slag.

[0010] Furthermore, in the above-mentioned method for direct online iron extraction from converter steel slag, in step 1), the liquid steel slag is stirred by a stirring paddle, and the tip of the stirring paddle blade is located at the surface of the liquid steel slag (within 200mm of vertical deviation).

[0011] Furthermore, in the above-mentioned method for direct online iron extraction from converter slag, in step 3), the material is cooled to a temperature below 600°C.

[0012] Compared with the prior art, the advantages of the present invention are: 1. The method of the present invention utilizes the sensible heat of the slag-iron separating agent when the steel slag temperature is high to separate the slag, iron and oxides, resulting in better separation effect and higher iron recovery rate.

[0013] 2. The method of the present invention uses stirring to make the steel slag rotate, and under the action of centrifugal force, the slag can be separated from iron and iron oxides.

[0014] The method of the present invention improves the fluidity of liquid steel slag by adding a slag-iron separator, making the slag thinner and flowing more smoothly, which facilitates slag-iron separation. Moreover, the slag-iron separation process can be completed without secondary heating, saving energy. This invention achieves excellent separation of waste slag and iron and iron oxides in converter steel slag through the combined action of rapid feeding, multi-point stirring and separation, and slag-iron separation agent, reducing the manpower and material resources required to separate the final slag from iron and iron oxides after steel slag treatment.

[0015] The method of this invention achieves an iron recovery rate of 15% to 20% in converter steel slag. Detailed Implementation

[0016] The steel slag treatment device used in the following embodiments is the device disclosed in Chinese Patent ZL202520538892.4.

[0017] The embodiments provided by this invention use a slag-iron separating agent with the following composition: 3-5% fluorite, 38-43% silica, 5-7% Al2O3 powder, and 47-52% carbon powder. Specifically, the composition of each component can be: 4% fluorite, 40% silica, 6% Al2O3 powder, and 50% carbon powder; or 4% fluorite, 43% silica, 6% Al2O3 powder, and 47% carbon powder; or 3% fluorite, 40% silica, 5% Al2O3 powder, and 52% carbon powder; or 4% fluorite, 38% silica, 6% Al2O3 powder, and 52% carbon powder; or 5% fluorite, 41% silica, 7% Al2O3 powder, and 47% carbon powder.

[0018] Example 1

[0019] A method for direct online iron extraction from converter steel slag includes the following steps: 1) Before the slag discharge during normal smelting in the converter, place the slag ladle under the furnace. The high-temperature liquid converter slag flows out from the converter opening until the discharge volume is reached. Then, quickly transfer the slag ladle containing the slag to the area under the special equipment for slag iron extraction. Transfer the high-temperature liquid converter slag into the slag ladle in one go. Stir the center and surrounding areas of the liquid slag. The tip of the stirring blade should be positioned on the surface of the liquid slag (within 200mm vertical deviation). Simultaneously, quickly add slag-iron separating agent to the center and surrounding areas of the liquid slag to ensure thorough mixing. 5kg of slag-iron separating agent is added per ton of slag. The composition of the slag-iron separating agent is: 4% fluorite, 40% silica, 6% Al2O3, and 50% C. Under stirring, the slag-iron separating agent comes into full contact with the liquid slag, reducing the viscosity of the liquid slag and promoting the dispersion and separation of waste slag, iron, and iron oxides. 2) After stirring for an appropriate time, stop stirring, remove the slag pot, and cool it. Because the density of composite converter slag is 2.7-3.0 g / cm³, the density of liquid FeO molten slag is 4.3-4.5 g / cm³, and the density of liquid pure iron is about 7.0 g / cm³, during the stirring process, the waste slag gradually floats to the top layer of the slag pot, the iron oxide gradually floats to the middle layer of the slag pot, and the iron gradually sinks to the bottom layer of the slag pot. During the cooling process, the waste slag, iron oxide, and iron solidify in layers from top to bottom in the slag pot. 3) After the material in the slag container has cooled to below 600℃, invert the cooled slag container onto the ground and pour out the slag. The slag and iron in the slag will naturally separate, and iron and iron oxides can be obtained.

[0020] The recovery rate of iron and its oxides was 15.3% as tested.

[0021] Example 2

[0022] A method for direct online iron extraction from converter steel slag includes the following steps: 1) Before the slag discharge during normal smelting in the converter, place the slag ladle under the furnace. High-temperature liquid converter slag flows out of the converter opening until the required discharge volume is reached. Then, quickly transfer the slag ladle to the area under the special equipment for slag-to-iron extraction. Transfer the high-temperature liquid converter slag into the slag ladle in one go. Stir the center and surrounding areas of the liquid slag, ensuring the blades of the stirring paddle are positioned on the surface of the liquid slag (within a vertical deviation of 200mm). Simultaneously, rapidly add slag-iron separating agent to the center and surrounding areas of the liquid slag to ensure thorough mixing. Add 10kg of slag-iron separating agent per ton of slag. The slag-iron separating agent consists of: 4% fluorite, 40% silica, 6% Al2O3, and 50% C. Under stirring, the slag-iron separating agent fully contacts the liquid slag, reducing its viscosity and promoting the dispersion and separation of waste slag, iron, and iron oxides. 2) After stirring for an appropriate time, stop stirring, remove the slag pot, and cool it. Because the density of composite converter slag is 2.7-3.0 g / cm³, the density of liquid FeO molten slag is 4.3-4.5 g / cm³, and the density of liquid pure iron is about 7.0 g / cm³, during the stirring process, the waste slag gradually floats to the top layer of the slag pot, the iron oxide gradually floats to the middle layer of the slag pot, and the iron gradually sinks to the bottom layer of the slag pot. During the cooling process, the waste slag, iron oxide, and iron solidify in layers from top to bottom in the slag pot. 3) After the material in the slag container has cooled to below 600℃, invert the cooled slag container onto the ground and pour out the slag. The slag and iron in the slag will naturally separate, and iron and iron oxides can be obtained.

[0023] Testing showed that the recovery rate of iron and its oxides was 18.1%. Example 3

[0024] A method for direct online iron extraction from converter steel slag includes the following steps: 1) Before the slag discharge during normal smelting in the converter, place the slag ladle under the furnace. High-temperature liquid converter slag flows out of the converter opening until the required discharge volume is reached. Then, quickly transfer the slag ladle to the area under the special equipment for slag iron extraction. Transfer the high-temperature liquid converter slag into the slag ladle in one go. Stir the center and surrounding areas of the liquid slag, ensuring the blades of the stirring paddle are positioned on the surface of the liquid slag (within a vertical deviation of 200mm). Simultaneously, rapidly add slag-iron separating agent to the center and surrounding areas of the liquid slag to ensure thorough mixing. Add 20kg of slag-iron separating agent per ton of slag. The slag-iron separating agent consists of: 4% fluorite, 40% silica, 6% Al2O3, and 50% C. Under stirring, the slag-iron separating agent fully contacts the liquid slag, reducing its viscosity and promoting the dispersion and separation of waste slag, iron, and iron oxides. 2) After stirring for an appropriate time, stop stirring, remove the slag pot, and cool it. Because the density of composite converter slag is 2.7-3.0 g / cm³, the density of liquid FeO molten slag is 4.3-4.5 g / cm³, and the density of liquid pure iron is about 7.0 g / cm³, during the stirring process, the waste slag gradually floats to the top layer of the slag pot, the iron oxide gradually floats to the middle layer of the slag pot, and the iron gradually sinks to the bottom layer of the slag pot. During the cooling process, the waste slag, iron oxide, and iron solidify in layers from top to bottom in the slag pot. 3) After the material in the slag container has cooled to below 600℃, invert the container onto the ground and pour out the slag. The slag and iron in the slag will naturally separate, yielding iron and iron oxides.

[0025] The recovery rate of iron and its oxides was 20.2% as tested.

Claims

1. A method for online iron extraction from converter steel slag, characterized in that, Includes the following steps: 1) The high-temperature liquid converter slag is transferred into the slag hopper in one go. The center and the surrounding area of ​​the liquid slag are stirred. At the same time, the slag-iron separation agent is quickly added to the center and the surrounding area of ​​the liquid slag to make the slag-iron separation agent and the liquid slag fully mixed. The components of the slag-iron separation agent are: fluorite, silica, Al2O3 powder and carbon powder. 2) After stirring for an appropriate time, stop stirring, remove the slag pot, and cool it. During the stirring process, the waste slag gradually floats to the top layer of the slag pot, the iron oxide gradually floats to the middle layer of the slag pot, and the iron gradually sinks to the bottom layer of the slag pot. During the cooling process, the waste slag, iron oxide, and iron solidify in layers from top to bottom in the slag pot. 3) After the material in the slag container has cooled down, invert the container to pour out the slag. The slag and iron in the slag will naturally separate, and iron and iron oxides can be obtained.

2. The method for online iron extraction from converter steel slag according to claim 1, characterized in that, The device used for steel slag treatment is the device disclosed in Chinese patents ZL 202520538892.4 or ZL202420743241.

4.

3. The method for online iron extraction from converter steel slag according to claim 1, characterized in that, In step 1), before pouring in the steel slag, a layer of anti-sticking agent is laid at the bottom of the steel slag container.

4. The method for online iron extraction from converter steel slag according to claim 1, characterized in that, In step 1), 5-20 kg of slag-iron separation agent is added per ton of steel slag.

5. The method for online iron extraction from converter steel slag according to claim 1, characterized in that, The composition of the slag-iron separator is: fluorite 3-5%, silica 38-43%, Al2O3 powder 5-7%, and carbon powder 47-52%.

6. The method for online iron extraction from converter steel slag according to claim 1, characterized in that, In step 1), the liquid steel slag is stirred by a stirring paddle, and the tip of the paddle blade is located on the surface of the liquid steel slag.

7. The method for online iron extraction from converter steel slag according to claim 1, characterized in that, In step 3), the material is cooled to a temperature below 600°C.