A method for separating metallic iron from zinc, manganese and nickel in pickling sludge and a preparation method thereof

Abstract

A method for separating metallic iron from zinc, manganese and nickel in pickling sludge. The method comprises grinding and sieving the pickling sludge after dechlorination salt drying with an appropriate amount of sulfating agent to a required particle size, and then placing the sludge in a tube furnace for roasting. The end of the tube needs to be connected to a device for collecting condensed and recycled waste gas. The obtained cooked roasted sand is treated with a water leaching process to obtain a sulfate leaching solution of zinc, nickel and manganese. Through strict condition control, the leaching rates of zinc, manganese and nickel in the pickling sludge can be greater than 93% respectively, while the leaching rate of iron is less than 2.3%, so that good selective separation of zinc, manganese, nickel and iron in the pickling sludge can be achieved, and iron-rich leaching slag that can be used as iron concentrate can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of pickling sludge resource treatment, and in particular to a method for separating metallic iron from zinc, manganese and nickel in pickling sludge and a preparation method thereof. Background Art

[0002] With the rapid development of my country's steel industry, a large amount of pickling sludge is generated in steel rust removal and other production links. On the one hand, the pickling sludge contains a large amount of toxic substances and belongs to the category of hazardous waste. According to environmental protection requirements, it cannot be directly discharged to avoid polluting the environment and harming human health. On the other hand, the pickling sludge contains a large amount of recyclable metal components. If it can be reasonably recycled, it can also generate greater economic value. Therefore, how to efficiently and high-quality recycle the pickling sludge is the main research and development direction.

[0003] Pickling sludge usually contains a large amount of iron oxides and a small amount of heavy metal oxides such as zinc, manganese, and nickel. At present, the methods proposed for the resource utilization of pickling sludge mainly include: mixing and grinding the dried pickling sludge with PCI coal to obtain mixed fine powder, and then using the mixed fine powder in the blast furnace coal injection process; using it as an ingredient for sintered ore; preparing cement, flocculants, microcrystalline glass, bricks, and ceramsite; high-temperature reduction smelting, acid leaching, and alkali dissolution by pyrometallurgy. These methods do not effectively separate and recycle the iron from zinc, manganese, and nickel in pickling acid sludge in a clean, efficient, and safe manner.

[0004] If the iron oxides in the pickling sludge are to be recovered as iron concentrate with high demand for use in ironmaking plants, the zinc in the sludge will cause expansion of the furnace lining and damage to the furnace shell after being reduced during smelting, and manganese and nickel, which are more valuable than iron, will cause waste of resources in the iron concentrate. Therefore, it is necessary to selectively separate the heavy metal oxides such as zinc, manganese, and nickel from the iron oxides in the sludge to facilitate the high-value resource utilization of the pickling sludge. Summary of the invention

[0005] The invention discloses a method for separating metallic iron from zinc, manganese and nickel in pickling sludge, which can effectively separate zinc, manganese, nickel and iron in pickling sludge and realize high-value resource utilization of pickling sludge.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for separating metallic iron from zinc, manganese and nickel in pickling sludge, characterized in that it comprises the following steps:

[0008] Step 1: fully mix the dechlorinated salt dried pickling sludge with the sulfating agent, and grind and sieve to a particle size of 150-80 μm;

[0009] Step 2: Put the evenly mixed roasting material obtained in step 1 into a high-temperature furnace. The end of the high-temperature furnace tube needs to be connected to a recovery device for collecting condensed and recycled waste gas. During the experiment, firstly, N2 is continuously introduced into the high-temperature furnace tube to completely remove the air in the high-temperature furnace tube and then the temperature is raised for roasting. The heating rate is set to 10°C / min, and the temperature is raised to the set temperature of 300-700°C. After constant temperature roasting for 30-270 minutes, the roasting material is naturally cooled to room temperature with the furnace, and the tail gas generated during the roasting process is absorbed in two stages by dilute sulfuric acid.

[0010] Step three, after the roasting in step two is completed, the roasting slag is weighed and ground to a fineness of <74 μm, and then the roasting slag is water-leached to dissolve the soluble sulfate in the roasting slag. After the water leaching is completed, the slurry is filtered by suction, and then the filter residue is washed with water 3 times, the volume of the filtrate is measured, the filter residue is collected and dried and ground, and the iron, zinc, manganese and nickel contents therein are analyzed to calculate the leaching rate.

[0011] Preferably, the amount of sulfating agent added in step 1 is 1.3-3 times the theoretical amount for converting all zinc oxides in the pickling sludge into ZnSO4.

[0012] Preferably, the amount of sulfating agent added in step 1 is 1.4 times the theoretical amount for converting all zinc oxides in the pickling sludge into ZnSO4.

[0013] Preferably, the sulfating agent in step 1 comprises ammonium sulfate or ammonium bisulfate.

[0014] Preferably, the particle size in step 1 is 100 μm.

[0015] Preferably, the high temperature furnace in step 2 is a muffle furnace, a tubular furnace or a rotary kiln.

[0016] Preferably, in step 2, the heating temperature is 500° C. and the calcination is carried out at a constant temperature for 150 minutes.

[0017] Preferably, the water leaching conditions in step three are: at room temperature, a solid-liquid ratio of 1:4 g / mL, a stirring speed of 200 r / min, and a leaching time of 40 min.

[0018] Compared with the existing technology, the present invention realizes the selective separation of zinc, manganese, nickel and iron in pickling sludge, which is more conducive to the high-value resource utilization of zinc, manganese, nickel and iron in pickling sludge. The sulfating agent ammonium sulfate used in the present invention is safer than sulfuric acid. When mixed with pickling sludge, it is easier to mix evenly, and the working environment is cleaner than when using sulfuric acid. The cooked roasted material of the present invention can be leached with water, without the need to add acid or alkali for leaching, and the cost is low. Ammonium bicarbonate can be added to the filtrate of the water leaching of the present invention to precipitate zinc to prepare basic zinc carbonate. The solution after the tail gas generated by the sulfation roasting is absorbed by the dilute sulfuric acid is (NH4)2SO4 solution. The solution is evaporated and concentrated to crystallize into (NH4)2SO4 crystals and can be returned to the sulfation roasting pickling sludge. The water leaching residue can be further magnetized roasted-magnetic separation to recover iron concentrate. The tail gas produced by sulphate roasting can also be directly introduced into the leaching solution, and then the pH is adjusted to precipitate zinc to obtain Zn(OH)2 precipitate and (NH4)2SO4 solution. After the (NH4)2SO4 solution reaches a certain concentration, the (NH4)2SO4 crystals are generated by crystallization method and can be reused in the sulphate roasting process. This not only effectively separates iron from zinc, manganese and nickel in pickling sludge, but also creates good conditions for the efficient recovery of metals such as Zn, Mn, Ni and Fe. The tail gas of the roasting process can also be reused, and the technical process can achieve efficient recycling of resources. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0020] Embodiment 1, a method for separating metallic iron from zinc, manganese and nickel in pickling sludge, comprising the following steps:

[0021] Step 1: fully mix the dechlorinated salt dried pickling sludge with the sulfating agent, and grind and sieve to a particle size of 150-80 μm;

[0022] Step 2: Put the evenly mixed roasting material obtained in step 1 into a high-temperature furnace. The end of the high-temperature furnace tube needs to be connected to a recovery device for collecting condensed and recycled waste gas. During the experiment, first, N2 is continuously introduced into the high-temperature furnace tube to completely exhaust the air in the high-temperature furnace tube and then start heating and roasting. The heating rate is set to 10°C / min. The temperature is raised to a set temperature of 300-700°C, preferably 400-650°C. After constant temperature roasting for 30-270min, more preferably 90-210min, the roasting material is naturally cooled to room temperature with the furnace, and the tail gas generated during the roasting process is absorbed in two stages by dilute sulfuric acid.

[0023] Step 3: After the roasting in step 2 is completed, the roasting slag is weighed and ground to a fineness of <74μm, and then the roasting slag is water-leached to dissolve the soluble sulfate in the roasting slag. After the water leaching is completed, the slurry is filtered by suction, and then the filter residue is washed with water 3 times. The volume of the filtrate is measured, and the filter residue is collected and dried and ground to analyze the iron, zinc, manganese, and nickel content therein, and the leaching rate is calculated. Under the conditions of a roasting temperature of 650°C and a roasting time of 210min, (NH4)2SO4 is 40% excessive, the particle size of the roasted material is 96-80μm, the leaching rates of zinc, manganese, and nickel can all exceed 93%, and the leaching rate of iron is less than 2.3%. The selective separation of zinc, manganese, nickel, and iron is achieved. Because the leached slag is the residue left after separating zinc, manganese, nickel and other components, the Fe content in the leached slag is increased, which can be higher than 63%, which is about 21% higher than before roasting. The Fe content in the leached slag meets the requirements of the quality standard of iron concentrate.

[0024] Example 2, in the method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to Example 1, the amount of sulfating agent added in step 1 is 1.3-3 times the theoretical amount of ZnSO4 required to convert all zinc oxides in the pickling sludge.

[0025] Example 3, in the method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to Example 1 or 2, the amount of sulfating agent added in step 1 is 1.4 times the theoretical amount of converting all zinc oxides in the pickling sludge into ZnSO4. According to the formula

[0026] ZnFe2O4(s)+ 4(NH4)2SO4(l) = ZnSO4(s)+ Fe2(SO4)3(s)+ 8NH3(g)+ 4H2O(g)

[0027] And Zn in the ZnSO4 molecular formula 2+ and SO4 2- Theoretically, 1g Zn requires 2.02g (NH4)2SO4, but in actual situations, since there are other impurities in the raw materials that can consume (NH4)2SO4, a certain excess coefficient is required to make the reaction complete.

[0028] Embodiment 4, in the method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to any one of embodiments 1 to 3, the sulfating agent in step 1 includes ammonium sulfate or ammonium bisulfate. The sulfating agent mainly refers to ammonium sulfate, ammonium bisulfate and other environmentally friendly agents that are easy to mix and grind with pickling sludge.

[0029] Example 5, in the method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to any one of Examples 1-4, the particle size in step 1 is 100 μm.

[0030] Example 6, in the method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to any one of Examples 1-5, the high-temperature furnace in step 2 is a muffle furnace, a tubular furnace or a rotary kiln.

[0031] Example 7, in the method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to any one of Examples 1-6, the heating temperature in step 2 is 500° C. and the constant temperature is maintained for 150 minutes.

[0032] Example 8. In the method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to any one of Examples 1-7, the water leaching conditions in step three are: at room temperature, a solid-liquid ratio of 1:4 g / mL, a stirring speed of 200 r / min, and a leaching time of 40 min.

[0033] Example 9, a method for separating metallic iron from zinc, manganese and nickel in pickling sludge, weigh 20g of pickling sludge after dechlorination, (NH4)2SO4 is 40% more than the theoretical amount, and the particle size is ≤150μm after mixing and grinding, and then flattened in a quartz boat and placed in a furnace tube. During the experiment, N2 is first continuously introduced into the furnace tube to completely remove the air in the furnace tube before heating and roasting. The heating rate is set to 10℃ / min, and the temperature is raised to 500℃ for roasting for 2h. After the roasting is completed, the roasting slag is weighed and ground to a fineness of <74μm, and then the roasting slag is soaked in water. Deionized water is used as the leaching agent during leaching, the leaching time is 40min at room temperature, the leaching liquid-solid ratio is 4, and the stirring speed is 200r / min. Under this condition, the leaching rates of Fe, Zn, Mn and Ni are 35%, 83%, 62% and 64% respectively.

[0034] Example 10, a method for separating metallic iron from zinc, manganese and nickel in pickling sludge, weigh 20g of pickling sludge after dechlorination and add 40% (NH4)2SO4 in excess of the theoretical amount, mix and grind to a particle size of ≤150μm, then lay it flat in a quartz boat and put it into a furnace tube. During the experiment, N2 was first continuously introduced into the furnace tube to completely remove the air in the furnace tube before heating and roasting. The heating rate was set to 10℃ / min, and the temperature was raised to 650℃ for roasting for 2h. After the roasting was completed, the roasting slag was weighed and ground to a fineness of <74μm, and then the roasting slag was soaked in water. Deionized water was used as the leaching agent during leaching, at room temperature, the leaching time was 40min, the leaching liquid-solid ratio was 4, and the stirring speed was 200r / min. Under this condition, the leaching rates of Fe, Zn, Mn and Ni were 9%, 88%, 78% and 82% respectively.

[0035] Example 11, a method for separating metallic iron from zinc, manganese and nickel in pickling sludge, weigh 20g of pickling sludge after dechlorination and add 40% (NH4)2SO4 in excess of the theoretical amount, mix and grind to a particle size of ≤150μm, then lay it flat in a quartz boat and put it into a furnace tube. During the experiment, N2 was first continuously introduced into the furnace tube to completely remove the air in the furnace tube before heating and roasting. The heating rate was set to 10℃ / min, and the temperature was raised to 650℃ for roasting for 3.5h. After the roasting was completed, the roasting slag was weighed and ground to a fineness of <74μm, and then the roasting slag was soaked in water. Deionized water was used as the leaching agent during leaching, at room temperature, the leaching time was 40min, the leaching liquid-solid ratio was 4, and the stirring speed was 200r / min. Under this condition, the leaching rates of Fe, Zn, Mn and Ni were 5%, 91%, 88% and 90% respectively.

[0036] Example 12, weigh 20g of pickled sludge after dechlorination and add 40% (NH4)2SO4 in excess of the theoretical amount, mix and grind to a particle size of 96-80μm, then lay it flat in a quartz boat and put it into a furnace tube. During the experiment, N2 was first continuously introduced into the furnace tube to completely remove the air in the furnace tube before heating and roasting. The heating rate was set to 10℃ / min, and the temperature was raised to 650℃ for roasting for 3.5h. After the roasting was completed, the roasted slag was weighed and ground to a fineness of <74μm, and then the roasted slag was soaked in water. Deionized water was used as the leaching agent for leaching, at room temperature, the leaching time was 40min, the leaching liquid-solid ratio was 4, and the stirring speed was 200r / min. Under this condition, the leaching rates of zinc, manganese and nickel can all exceed 93%, and the leaching rate of iron is less than 2.3%.

[0037] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for separating metallic iron from zinc, manganese and nickel in pickling sludge, characterized in that: The following steps are involved: Step 1: fully mix the dechlorinated salt dried pickling sludge with the sulfating agent, and grind and sieve to a particle size of 150-80 μm; The amount of sulfating agent added in step 1 is 1.3-3 times the theoretical amount of ZnSO4 to convert all zinc oxides in the pickling sludge; In the step 1, the sulfating agent includes ammonium sulfate or ammonium bisulfate; Step 2: Put the evenly mixed roasting material obtained in step 1 into a high-temperature furnace. The end of the high-temperature furnace tube needs to be connected to a recovery device for collecting condensed and recycled waste gas. During the experiment, firstly, N2 is continuously introduced into the high-temperature furnace tube to completely remove the air in the high-temperature furnace tube and then the temperature is raised for roasting. The heating rate is set to 10°C / min, and the temperature is raised to the set temperature of 300-700°C. After constant temperature roasting for 30-270 minutes, the roasting material is naturally cooled to room temperature with the furnace, and the tail gas generated during the roasting process is absorbed in two stages by dilute sulfuric acid. Step three, after the roasting in step two is completed, the roasting slag is weighed and ground to a fineness of <74 μm, and then the roasting slag is water-leached to dissolve the soluble sulfate in the roasting slag. After the water leaching is completed, the slurry is filtered by suction, and then the filter residue is washed with water 3 times, the volume of the filtrate is measured, the filter residue is collected and dried and ground, and the iron, zinc, manganese and nickel contents therein are analyzed to calculate the leaching rate.

2. The method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to claim 1, characterized in that: The amount of sulfating agent added in step 1 is 1.4 times the theoretical amount for converting all zinc oxides in the pickling sludge into ZnSO4.

3. The method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to claim 1, characterized in that: The particle size in step 1 is 100 μm.

4. The method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to claim 1, characterized in that: The high temperature furnace in step 2 is a muffle furnace, a tubular furnace or a rotary kiln.

5. The method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to claim 1, characterized in that: In the step 2, the temperature is raised to 500° C. and the calcination is carried out at a constant temperature for 150 minutes.

6. The method for separating metallic iron from zinc, manganese and nickel in pickling sludge according to claim 1, characterized in that: The water leaching conditions in step 3 are: at room temperature, a solid-liquid ratio of 1:4 g / mL, a stirring speed of 200 r / min, and a leaching time of 40 min.