Oil removal and resource utilization method for hot-rolled silt

Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to solid waste environment-friendly treatment and resource utilization in the metallurgical industry, in particular to a hot-rolled silt oil removal and resource utilization method which comprises the following steps: 1) stirring silt in deionized water; 2) adding a cleaning agent and a builder, and stirring at room temperature until the pH value of the mixed solution is more than or equal to 8 and less than or equal to 12; 3) standing the mixed solution to realize separation of oil and iron in the silt; and rinsing the separated iron sludge with deionized water to respectively obtain an oil-containing filtrate and iron-containing sludge. And (4) the oil-containing filtrate is recycled, the iron-containing silt is dried in a drying oven, the oil content of the dried iron-containing silt is smaller than 5%, the water content of the dried iron-containing silt is 7%-15%, the particle size of the dried iron-containing silt is smaller than 3 mm after crushing and screening, and the iron-containing silt is used as a sintering ingredient. The iron resource utilization rate is increased, solid waste emission is greatly reduced, and the iron ore purchasing and waste treatment cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of metallurgical technology, and particularly relates to the environmental protection treatment and resource utilization of solid waste in the metallurgical industry. Specifically, it is a method for removing oil and resource utilization of hot-rolled sludge. Background Art

[0002] During the steel production process, a large amount of hot-rolled sludge is generated in the hot-rolling process. In 2023, the output of hot-rolled strip steel in China was approximately 400 million tons, and the annual output of hot-rolled sludge was approximately 1.2 million tons. With the continuous expansion of the scale of the steel industry, the output of hot-rolled sludge has also been increasing day by day, and its reasonable disposal has become an urgent problem faced by steel enterprises.

[0003] Traditionally, due to the relatively high oil content, hot-rolled sludge is usually regarded as waste and stacked or simply landfilled. On the one hand, this not only occupies a large amount of precious land resources, but also over time, the oil in the sludge will gradually seep out, causing serious pollution to the soil and surrounding water bodies, triggering a series of environmental problems, such as the decline of soil fertility and water eutrophication. On the other hand, from the perspective of resource recovery and utilization, hot-rolled sludge is by no means a "waste product" without value. Hot-rolled sludge contains rich valuable elements such as iron, calcium, and silicon. If it can be effectively utilized, it is of great significance for reducing the raw material cost of steel production and improving the comprehensive utilization rate of resources.

[0004] In the sintering burdening process, enterprises have always relied on traditional raw materials such as iron ore and limestone, and the procurement cost is relatively high. If the hot-rolled sludge after oil removal treatment can be successfully applied to sintering burdening, it can not only realize the resourceization of waste, reduce the dependence on external raw materials, but also relieve the cost pressure and environmental pressure faced by steel enterprises to a certain extent.

[0005] The current disposal status of hot-rolled sludge is not optimistic. Traditional treatment methods, such as simple landfilling or incineration, not only cannot fully exploit its internal value, but also bring about many drawbacks. The landfill method needs to occupy a large amount of precious land resources, and over time, the environmental problems around the landfill site will become increasingly prominent; the incineration method will generate a large amount of harmful gases and dust, causing secondary pollution to the atmospheric environment and exacerbating the formation of bad weather such as haze. At the same time, some existing oil removal and resource utilization technologies either have high treatment costs, discouraging enterprises, or have poor treatment effects and cannot meet the strict quality requirements of steel production, making it difficult to truly turn hot-rolled sludge into treasure. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for removing oil and resource utilization of hot-rolled sludge, aiming to improve the iron resource utilization rate, relieve the environmental protection pressure, and reduce the waste disposal cost.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for removing oil and resource utilization from hot-rolled sediment sludge, comprising the following method steps:

[0009] 1) Take the sediment sludge at the bottom of the horizontal flow tank in a hot-rolling plant of a steel enterprise and mechanically stir it evenly in deionized water at room temperature, where the mass solid-liquid ratio of the sediment sludge to deionized water is 1:(10-20).

[0010] 2) Add a cleaning agent and a washing aid to the solid-liquid mixture in step 1). The cleaning agent is a compound solution of a non-ionic surfactant and an anionic surfactant. The mass compounding ratio of the non-ionic surfactant to the anionic surfactant in the cleaning agent is (3-1):1, and the concentration of the cleaning agent solution is 3%-10%; the concentration of the washing aid is 1%-8%; continuously mechanically stir at room temperature for 15-20 min to obtain a mixed solution, the stirring rate is 300-700 rpm, and the pH value range of the mixed solution is 8 ≤ pH ≤ 12.

[0011] 3) Let the mixed solution obtained in step 2) stand for 5-10 min. The oil layer floats up and the iron sludge sinks, realizing the separation of oil and iron in the sediment sludge; the separated iron sludge is rinsed with deionized water to remove the residual chemicals and oil on the surface, and an oil-containing filtrate and iron-containing sediment sludge are obtained respectively.

[0012] 4) Recover the oil-containing filtrate obtained in step 3). The iron-containing sediment sludge is dried in an oven at 100-150 °C for 10-24 h. The oil content rate of the dried iron-containing sediment sludge is <5%, the water content is 7%-15%, and the particle size after crushing and screening is <3 mm, which is used as a sintering burden.

[0013] The non-ionic surfactant is one of fatty alcohol polyoxyethylene ether (AEO), Turkey red oil, octylphenol polyoxyethylene ether (TX), and coconut oil fatty acid diethanolamide (6501). The hydrophilic group and hydrophobic group in the non-ionic surfactant molecule are relatively balanced and will not ionize into ions in the solution. It mainly binds to water molecules through hydrogen bonds and has good water solubility and stability. When cleaning hot-rolled sediment sludge, the hydrophobic group of the non-ionic surfactant will interact with the oil phase in the oil sludge, while the hydrophilic group will interact with the water phase, thereby reducing the surface tension between oil and water, enabling the oil droplets to be better dispersed in water to form a stable emulsion, achieving the purpose of cleaning.

[0014] The anionic surfactant is one of sodium dodecylbenzenesulfonate (LAS) and triethanolamine. An anionic surfactant can ionize negatively charged ions in water, and its hydrophilic groups are usually carboxylates, sulfonates, sulfates, etc. When cleaning hot-rolled sludge, the anionic part of the anionic surfactant will interact with the oil phase in the sediment, and at the same time its negatively charged ions will attract the positive charges on the metal surface, making it easier for oil droplets to detach from the metal surface.

[0015] The builder is one or more of sodium tripolyphosphate (STPP), sodium silicate, and sodium sulfate. Sodium tripolyphosphate can chelate metal ions in water, prevent metal ions from combining with oil stains to form substances that are difficult to clean, and at the same time it can also disperse dirt particles and oil droplets, reduce the drastic pH changes caused by the addition or reaction of other substances, and ensure that the cleaning process is carried out within an appropriate pH range; Sodium silicate can provide an alkaline environment and can also adsorb on the surface of dirt, making the dirt suspended in the cleaning solution and preventing the dirt from redepositing. Sodium sulfate can adjust the density and viscosity of the cleaning solution, which helps the cleaning solution to better penetrate into the sediment and makes it easier for dirt and oil droplets to be dispersed and emulsified.

[0016] The chemical composition and mass percentage of the hot-rolled sediment are as follows: C: 3% - 10%, S: 0.05% - 0.5%, TFe: 50% - 75%, FeO: 10% - 30%, Fe2O3: 20% - 40%, SiO2: 0.5% - 8%, Al2O3: 1% - 5%, CaO: 1% - 5%, MgO: 0.5% - 3%, P: 0.04% - 0.2%, K2O < 0.01%, Na2O < 0.01%. The loss on ignition (LOI) of the hot-rolled sediment is 3% - 15%; the oil content is 7% - 12%.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] On the one hand, from the perspective of resource utilization, the present invention can re-convert waste hot-rolled sediment into valuable sintering raw materials, improve the utilization rate of iron resources, and strongly promote the circular economy development of the steel industry; on the other hand, at the environmental protection level, it greatly reduces the emission of solid waste and effectively reduces the risk of sediment polluting the environment; furthermore, in terms of economic benefits, it reduces the procurement cost of iron ore and the waste treatment cost, brings significant profit space for enterprises, and helps sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail below with reference to the drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0021] Example 1:

[0022] The hot-rolled sludge in this example is the sludge at the bottom of the horizontal flow tank in the hot-rolling plant of a steel enterprise. The chemical components and their mass percentages are as follows: C: 6.1%, S: 0.108%, TFe: 69.53%, FeO: 26.24%, Fe2O3: 33.87%, SiO2: 0.56%, Al2O3: 1.26%, CaO: 1.37%, MgO: 0.52%, P: 0.042%, K2O: 0.0055%, Na2O: 0.0089%, loss on ignition LOI: 3.27%; the oil content of the sludge is 8.7%.

[0023] See Figure 1 , a method for removing oil and resource utilization of hot-rolled sludge is as follows:

[0024] 1) Take the sludge at the bottom of the horizontal flow tank in the hot-rolling plant of a steel enterprise in deionized water and mechanically stir evenly at room temperature. The mass solid-liquid ratio of the sludge to deionized water is 1:10.

[0025] 2) Add a compound solution of non-ionic surfactant fatty alcohol polyoxyethylene ether (AEO) and anionic surfactant sodium dodecylbenzenesulfonate (LAS) and builder sodium tripolyphosphate (STPP) to step 1). The mass compounding ratio of fatty alcohol polyoxyethylene ether (AEO) to sodium dodecylbenzenesulfonate (LAS) is 3:1, the concentration of the cleaning agent is 5%, and the concentration of the builder is 3%. Continuously mechanically stir at room temperature for 15 min to obtain a mixed solution. The stirring rate is 400 rpm, and the pH value of the mixed solution is 11.

[0026] 3) Let the mixed solution obtained in step 2) stand for 5 min. The oil layer floats and the iron sludge sinks, realizing the separation of oil and iron in the sludge; the separated sludge is rinsed with deionized water to remove the residual cleaning agent and oil on the surface, obtaining an oil-containing filtrate and iron-containing sludge.

[0027] 4) Recover the oil-containing filtrate obtained in step 3). The iron-containing sludge is dried in an oven at 120 °C for 12 h. The oil content of the iron sludge is 2.83%, the water content is 10%, and the particle size of the iron-containing sludge after crushing and screening is 2.1 mm, which is used as sintering burden.

[0028] Example 2:

[0029] The hot-rolled sludge in this example is the bottom sludge of the horizontal flow tank in the hot-rolling mill of a steel enterprise. The chemical components and their mass percentages are as follows: C: 4.6%, S: 0.092%, TFe: 71.35%, FeO: 28.51%, Fe2O3: 31.75%, SiO2: 0.62%, Al2O3: 1.93%, CaO: 1.67%, MgO: 0.59%, P: 0.051%, K2O: 0.0035%, Na2O: 0.0072%, loss on ignition LOI: 3.34%; the oil content of the sludge is 9.3%.

[0030] See Figure 1 , a method for removing oil and resource utilization of hot-rolled sludge is as follows:

[0031] 1) Take the bottom sludge of the horizontal flow tank in the hot-rolling mill of a steel enterprise and place it in deionized water, and mechanically stir it evenly at room temperature.

[0032] 2) Add a compound solution of non-ionic surfactant Turkey red oil and anionic surfactant sodium dodecylbenzenesulfonate (LAS) and washing aid sodium silicate to step 1). The compound ratio of the cleaning agent is 1:1, the concentration of the cleaning agent is 5%, and the concentration of the washing aid is 5%. Continuously mechanically stir at room temperature for 15 min to obtain a mixed solution. The stirring rate is 500 rpm, and the pH value of the mixed solution is 12.

[0033] 3) Let the mixed solution obtained in step 2) stand for 6 min. The oil layer floats and the iron sludge sinks to separate the oil and iron in the sludge; the separated sludge is rinsed with deionized water to remove the residual cleaning agent and oil on the surface, and an oil-containing filtrate and iron-containing sludge are obtained.

[0034] 4) Recover the oil-containing filtrate obtained in step 3). The iron-containing sludge is dried in an oven at 120 °C for 12 h. The oil content of the iron sludge is 1.43%, the water content is 8%, and the particle size of the iron-containing sludge after crushing and screening is 1.3 mm, which is used as sintering burden.

[0035] Example 3:

[0036] The hot-rolled sludge in this example is the bottom sludge of the horizontal flow tank in the hot-rolling mill of a steel enterprise. The chemical components and their mass percentages are as follows: C: 5.8%, S: 0.136%, TFe: 65.35%, FeO: 26.13%, Fe2O3: 30.85%, SiO2: 0.82%, Al2O3: 1.67%, CaO: 1.34%, MgO: 0.61%, P: 0.072%, K2O: 0.0068%, Na2O: 0.0093%, loss on ignition LOI: 4.53%; the oil content of the sludge is 10.8%.

[0037] See Figure 1 , a method for removing oil and resource utilization of hot-rolled sludge is as follows:

[0038] 1) Take the sediment at the bottom of the horizontal flow tank in a hot rolling mill of a steel enterprise and mix it evenly in deionized water under room temperature by mechanical stirring.

[0039] 2) Add a compound solution of a non-ionic surfactant coconut oil fatty acid diethanolamide (6501) and an anionic surfactant triethanolamine and a washing aid sodium sulfate to the step 1). The compound ratio of the cleaning agent is 2:1, the concentration of the cleaning agent is 10%, and the concentration of the washing aid is 8%. Continuously mechanically stir for 15 min at room temperature to obtain a mixed solution. The stirring rate is 500 rpm, and the pH value of the mixed solution is 9.

[0040] 3) Let the mixed solution obtained in the step 2) stand for 8 min. The oil layer floats up and the iron sludge sinks, realizing the separation of oil and iron in the sediment. The separated sediment is rinsed with deionized water to remove the residual cleaning agent and oil on the surface, obtaining an oil-containing filtrate and an iron-containing sediment.

[0041] 4) Recover the oil-containing filtrate obtained in the step 3). The iron-containing sediment is dried in an oven at 120 °C for 12 h. The oil content of the iron sludge is 3.12%, the water content is 11%, and the particle size of the iron-containing sediment after crushing and screening is 2.7 mm, which is used as a sintering burden.

[0042] Example 4:

[0043] The hot rolling sediment in this example is the sediment at the bottom of the horizontal flow tank in a hot rolling mill of a steel enterprise. The chemical components and mass percentages are as follows: C: 8.9%, S: 0.456%, TFe: 72.5%, FeO: 26.8%, Fe2O3: 36.44%, SiO2: 0.66%, Al2O3: 3%, CaO: 4%, MgO: 2.6%, P: 0.12%, K2O: 0.0055%, Na2O: 0.0090%, loss on ignition LOI: 10.3%; the oil content of the sediment is 6.5%.

[0044] See Figure 1 , a method for removing oil and resource utilization of hot rolling sediment, as follows:

[0045] 1) Take the sediment at the bottom of the horizontal flow tank in a hot rolling mill of a steel enterprise and mix it evenly in deionized water under room temperature by mechanical stirring.

[0046] 2) Add a compound solution of a non-ionic surfactant octylphenol polyoxyethylene ether and an anionic surfactant triethanolamine and a washing aid sodium sulfate to the step 1). The compound ratio of the cleaning agent is 2:1, the concentration of the cleaning agent is 5%, and the concentration of the washing aid is 4%. Continuously mechanically stir for 18 min at room temperature to obtain a mixed solution. The stirring rate is 600 rpm, and the pH value of the mixed solution is 11.

[0047] 3) Leave the mixed solution obtained in step 2) to stand for 6 min. The oil layer floats up and the iron sludge sinks, realizing the separation of oil and iron in the sludge. The separated sludge is rinsed with deionized water to remove the residual cleaning agent and oil on the surface, obtaining an oil-containing filtrate and iron-containing sludge.

[0048] 4) Recover the oil-containing filtrate obtained in step 3). The iron-containing sludge is dried in an oven at 140 °C for 11 h. The oil content of the iron sludge is 2.13% and the water content is 9%. After crushing and screening, the particle size of the iron-containing sludge is 1.8 mm, which is used as a sintering burden.

Claims

1. A method for removing oil from hot-rolled sediment and resource utilization, characterized in that The method comprises the following steps: 1) Take the sludge from the hot rolling mill advection tank and add it to deionized water, then mechanically stir it evenly at room temperature, wherein the mass solid-to-liquid ratio of the sludge to deionized water is 1:(10-20); 2) adding a detergent and a builder to the solid-liquid mixture of step 1), wherein the detergent is a composite solution of a nonionic surfactant and an anionic surfactant, the mass ratio of the nonionic surfactant to the anionic surfactant in the detergent is (3-1):1, the concentration of the detergent solution is 3%-10%, and the concentration of the builder is 1%-8%; and continuously mechanically stirring at room temperature to obtain a mixed solution, wherein the pH value of the mixed solution is in the range of 8≤pH≤12; 3) The mixed solution obtained in step 2) is allowed to stand for 5 to 10 minutes, the oil layer floats up, and the iron sludge sinks, thereby separating the oil and iron in the sludge; the separated iron sludge is rinsed with deionized water to remove the residual agent and oil on the surface, thereby obtaining an oil-containing filtrate and an iron-containing sludge, respectively. 4) The oil-containing filtrate obtained in step 3) is recovered, and the iron-containing sludge is dried in an oven. The iron-containing sludge after drying has an oil content of less than 5% and a moisture content of 7% to 15%. The particle size after crushing and screening is less than 3 mm, and is used as a sintering ingredient.

2. The hot rolling sludge oil removal and resource utilization method according to claim 1, wherein The nonionic surfactant is one of fatty alcohol polyoxyethylene ether, Taiko oil, octylphenol polyoxyethylene ether and coconut oil fatty acid diethanolamide.

3. A hot-rolling sludge oil removal and resource utilization method according to claim 1, characterized in that The anionic surfactant is one of sodium dodecylbenzenesulfonate and triethanolamine.

4. A hot-rolling sediment oil removal and resource utilization method according to claim 1, characterized in that, The builder is one or more of sodium tripolyphosphate, sodium silicate and sodium sulfate.

5. A hot rolling sludge oil removal and resource utilization method according to claim 1, characterized in that, In the step 2), the mechanical stirring time is 15 to 20 minutes, and the stirring rate is 300 to 700 rpm.

6. The method for hot-rolling sludge oil removal and resource utilization according to claim 1, characterized in that, The temperature of the oven is 100-150° C., and the drying time is 10-24 hours.

7. A hot-rolling sludge oil removal and resource utilization method according to any one of claims 1-6, characterized in that The chemical composition and mass percentage of the hot rolling sludge are: C: 3% to 10%, S: 0.05% to 0.5%, TFe: 50% to 75%, FeO: 10% to 30%, Fe2O3: 20% to 40%, SiO2: 0.5% to 8%, Al2O3: 1% to 5%, CaO: 1% to 5%, MgO: 0.5% to 3%, P: 0.04% to 0.2%, K2O < 0.01%, and Na2O < 0.01%.

8. A hot-rolling sediment oil removal and resource utilization method according to claim 7, characterized in that The hot rolling sludge has a loss on ignition (LOI) of 3% to 15% and an oil content of 7% to 12%.

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