Method for recovering heavy metals by co-sintering iron tailings with alkaline etching powder

Abstract

The application discloses a method for recovering heavy metals by co-calcining iron tailings and alkaline etching powder, and particularly relates to the technical field of mineral extraction. The method comprises the following steps: S1, drying alkaline etching waste liquid to obtain alkaline etching powder; S2, mixing the dried iron tailings and the alkaline etching powder and then performing chlorination calcination; and S3, cooling and washing the mixture obtained after the calcination to recover heavy metals. In step S2, the mass ratio of the iron tailings to the alkaline etching powder is greater than or equal to 1:0.03; the chlorination calcination temperature is 400-800 DEG C; the chlorination calcination time is greater than or equal to 20 min; in step S3, the solid-liquid ratio of the washing is greater than or equal to 1:1; and the washing time is greater than or equal to 20 min. The application can recover heavy metal resources in the iron tailings while treating the alkaline etching waste liquid, the heavy metal recovery rate is greater than 80%, and the clean production goal of treating waste with waste is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mineral extraction, in particular to a method for recovering heavy metals by co-combustion of iron tailings and alkaline etching powder. BACKGROUND

[0002] Iron tailings are typical bulk mining solid waste, which are usually treated by stacking in a tailings pond. The leaching of heavy metals in iron tailings not only destroys the ecological environment, but also wastes the iron resources in iron tailings. Iron tailings are usually a kind of symbiotic mineral containing multiple metal elements, mainly containing iron resources, but also containing heavy metals such as lead, zinc, copper, manganese and nickel. Due to the low content of heavy metals other than iron (about 1% in total), traditional wet extraction methods such as sulfuric acid leaching, heap leaching and roasting-ammonia leaching have problems such as low treatment efficiency and serious metal loss. Chlorination roasting technology can effectively utilize and recover heavy metals (Pb, Zn, Cu, Mn) in it, and is widely used in the treatment of waste lithium batteries, minerals, electroplating sludge and the like, providing an effective way for the recovery of heavy metals.

[0003] Alkaline etching waste liquid is a waste liquid generated by treating printed circuit boards with alkaline copper-containing etching liquid, and mainly contains Cu(NH3)4Cl2, ammonia water, ammonium chloride and the like. The copper content is 90-140 g / L, and the chlorine content is 100-140 g / L. If the alkaline etching waste liquid can be effectively recovered and treated, not only the value of copper in the alkaline etching waste liquid can be utilized, but also the environmental hazards caused by it can be reduced. At present, the main methods for treating alkaline copper-containing etching waste liquid include chemical precipitation, liquid membrane separation, electrolysis and solvent extraction to recover copper resources, but these methods have problems such as easy secondary pollution, high cost and unsatisfactory effect.

[0004] The prior art discloses a research on recovery of heavy metals Cu, Pb and Zn in iron tailings by CaCl2 chlorination roasting. In the research, CaCl2 is used as a chlorination salt to mix and chlorinate with iron tailings under a nitrogen atmosphere, so as to convert the heavy metals in the iron tailings into metal chlorides, and the heavy metals in the iron tailings are recovered by collecting the volatilized substances in the roasting process. Under a nitrogen atmosphere, the chlorination roasting temperature is 600℃, and the volatilization rates of Cu, Pb and Zn are about 25%, 92% and 30% respectively, i.e. the recovery rates of Cu, Pb and Zn are only 25%, 92% and 30% respectively. SUMMARY

[0005] In order to solve the problems of low recovery rate and complex recovery mode of heavy metals in iron tailings in the existing chloridizing roasting process, a method for recovering heavy metals by co-roasting iron tailings and alkaline etching powder is provided. The alkaline etching powder is obtained by dewatering the alkaline etching waste liquid, and the iron tailings and the alkaline etching powder are chloridizing roasted to generate heavy metal chlorides or heavy metal complexes, which are recovered by water washing. The method recovers heavy metal resources in the iron tailings while treating the alkaline etching waste liquid, and realizes waste treatment with waste, reduces cost and achieves the clean production goal.

[0006] The above-mentioned purpose of the present application is realized by the following technical solutions.

[0007] A method for recovering heavy metals by co-roasting iron tailings and alkaline etching powder, comprising the following steps:

[0008] S1, drying the alkaline etching waste liquid to obtain alkaline etching powder;

[0009] S2, mixing the dried iron tailings and the alkaline etching powder and then chloridizing roasting;

[0010] S3, cooling and water washing the mixture obtained after roasting to recover heavy metals;

[0011] In the step S2, the mass ratio of iron tailings to alkaline etching powder is greater than or equal to 1:0.03, the chloridizing roasting temperature is 400-800 DEG C, and the chloridizing roasting time is greater than or equal to 20 min;

[0012] In the step S3, the solid-liquid ratio of water washing is greater than or equal to 1:1, and the water washing time is greater than or equal to 20 min.

[0013] It should be noted that:

[0014] In the present application, the drying of iron tailings and the dewatering method of alkaline etching waste liquid can be drying in an oven at 60-105 DEG C for 24 h. The alkaline etching waste liquid is a copper-containing liquid waste, and the main components include Cu(NH3)4Cl2, ammonia water, ammonium chloride, etc. Currently, chemical precipitation method, liquid membrane separation method, electrolysis method, solvent extraction method, etc. are mainly used to recover copper resources therein, but the resource utilization efficiency is low, secondary pollution is serious, and the cost is high. After drying the alkaline etching waste liquid, the main components are NH4Cl, NaCl and copper ammonia complex, etc. NH3 and HCl gases are generated by heating NH4Cl or NaCl, etc. which can be used as chlorinating agent for iron tailings chloridizing roasting, and heavy metals such as lead, zinc, copper and manganese in iron tailings are converted into heavy metal chlorides or heavy metal complexes, which are then washed out by water.

[0015] In addition, the mixed chlorinating agent of the copper ammonia complex and ammonium chloride has a heavy metal conversion efficiency 10% higher than that of the monochloride ammonium chloride chlorinating agent at the same temperature, and the main reason is that the decomposition of the copper ammonia complex is stepwise (as shown in the following chemical reaction equations (1)-(3)), so that the heavy metal oxide can better react with NH3 to form a heavy metal complex. Compared with the reaction of the heavy metal oxide with NH3 and HCl after the decomposition of the ammonium chloride, the copper ammonia complex increases the amount and residence time of NH3, so that the complexation reaction of the heavy metal is more easily carried out, thereby improving the conversion efficiency of the heavy metal.

[0016]

[0017]

[0018]

[0019] In the specific embodiment of the present application, considering the economic benefits of the iron tailings and the heavy metal recovery problem in the chlorination roasting process, the dried iron tailings and the dried alkaline etching powder can be crushed, passed through a 200-mesh screen and then mixed uniformly, and then placed in the same closed container for chlorination roasting. By crushing and uniformly mixing the iron tailings and the alkaline etching powder, the thermal decomposition of the alkaline etching powder and the chlorination roasting reaction of the iron tailings are facilitated, so that the chlorine-containing atmosphere in the roasting process can fully contact with the heavy metal, converting the heavy metal oxide into its chloride or heavy metal complex, which is beneficial to improving the recovery rate of the heavy metal in the subsequent water leaching process.

[0020] The present application can recover heavy metals in iron tailings by chlorination roasting because heavy metal oxides or sulfides can react with chlorinating agents (HCl, Cl2, NH4Cl, CaCl2, etc.) at high temperatures to convert them into heavy metal chlorides or heavy metal complexes, which can be recovered by water washing or volatilization.

[0021] Preferably, the concentration of chloride ions in the alkaline etching waste liquid in step S1 is 100-140 g / L, because the main components of the alkaline etching liquid are CuCl2·2H2O, NH3·H2O and NH4Cl. By adjusting the ratio of NH4Cl to NH3·H2O, the etching liquid can achieve the purpose of etching Cu on the PCB circuit board. The main etching equation is as follows:

[0022] Cu+2NH4Cl+2NH3+0.5O2 = Cu(NH3)4Cl2+H2O (4)

[0023] When the amount of NH3·H2O and NH4Cl is insufficient, CuCl2 is converted into Cu(OH)2 precipitate, which cannot achieve the purpose of etching. The equation is as follows:

[0024]

[0025] Therefore, sufficient NH4Cl is added to make it reactive to Cu, and the concentration of Cl- in the alkaline etching waste liquid after etching is 100-140 g / L.

[0026] Preferably, the content of Pb, Zn, Cu and Mn in the iron tailings in step S2 is less than 10 mg / g, respectively.

[0027] The content of Pb, Zn, Cu and Mn in the iron tailings in the present application is ≤10 mg / g because when the content of heavy metals is greater than 10 mg / g, a large amount of chlorinating agent needs to be added, and too much chlorinating agent will produce too much HCl gas, which has certain corrosiveness and will corrode the equipment, reducing the economy of the present application, therefore, the preferred iron tailings in the present application have a heavy metal content of less than 10 mg / g, respectively.

[0028] Preferably, the mass ratio of iron tailings to alkaline etching powder in step S2 is ≥1:0.03, and further, the mass ratio of iron tailings to alkaline etching powder is 1:0.03-0.3.

[0029] Within this range of raw material mass ratio, it can better cooperate with the chlorination roasting temperature and time. By controlling the mass ratio of iron tailings powder to alkaline etching powder, the content of chlorine and ammonia provided by the alkaline etching powder can be controlled, and the heavy metals in the iron tailings and the alkaline etching waste liquid can be recovered to the maximum extent. When the proportion of alkaline etching powder is too high, it has little effect on the leaching recovery rate of Cu in the alkaline etching waste liquid and heavy metals in the iron tailings, because the heavy metals in the iron tailings have reacted with the chlorinating agent to form heavy metal chlorides or heavy metal complexes, and it is unnecessary to continue to increase the amount of alkaline etching powder. When the proportion of alkaline etching powder is too low, the chlorinating agent provided is not enough to chlorinate or complex all the heavy metals in the iron tailings, and the recovery rate of heavy metals after water leaching is lower than 80%.

[0030] More preferably, the mass ratio of iron tailings to alkaline etching powder in step S2 is 1:0.03-0.1, and further, the mass ratio of iron tailings to alkaline etching powder is 1:0.05.

[0031] Preferably, the chlorination roasting temperature in step S2 is 400-800℃.

[0032] The chlorination roasting temperature range can be better coordinated with the raw material mass ratio and the chlorination roasting time. When the chlorination roasting temperature is too low, the chlorination roasting atmosphere provided by the pyrolysis of the alkaline etching powder is insufficient to chlorinate or complex all the heavy metal resources in the iron tailings, and the heavy metal recovery rate after water immersion recovery is lower than 80%; when the chlorination roasting temperature is too high, the heavy metal chlorides can be converted into a gas phase and then discharged, which cannot be recovered by water immersion, resulting in that the heavy metal recovery rate cannot reach 80%.

[0033] More preferably, the chlorination roasting temperature is 400-600℃, and further, the chlorination roasting temperature is 450-550℃.

[0034] Preferably, the chlorination roasting time in step S2 is greater than or equal to 20 min, and further, the chlorination roasting time is 20-120 min.

[0035] In the chlorination roasting time range, the chlorination roasting time can be better coordinated with the raw material mass ratio and the chlorination roasting temperature. When the chlorination roasting time is too long, after the chlorination roasting reaction is completed, no other reaction will occur by continuing to roast the heavy metal chlorides and the heavy metal complexes, and from the economic point of view, the roasting cost required by the longer roasting time is higher, and the economic benefit decreases; when the chlorination roasting time is too short, the heavy metal and the chlorination agent do not react completely, resulting in poor heavy metal recovery effect, and the heavy metal recovery rate is lower than 80%.

[0036] More preferably, the chlorination roasting time is 20-50 min, and further, the chlorination roasting time is 30 min.

[0037] Preferably, the water washing solid-liquid ratio in step S3 is greater than or equal to 1:1, and further, the water washing solid-liquid ratio is 1:1-50.

[0038] Because when the solid-liquid ratio is too large, the dissolution equation The concentration of Cl - and Me n+ increases rapidly, which makes the reaction proceed in the reverse direction, and the reaction time increases. When the solid-liquid ratio is continuously small, the dissolution rate tends to be stable, and further increasing the solvent has no effect on the technical effect of the present application, but will waste the solvent, which is not good in economic performance.

[0039] More preferably, the water washing solid-liquid ratio in step S3 is 1:5-50, and further, the water washing solid-liquid ratio is 1:10.

[0040] When the solid-liquid ratio is 1:10, each heavy metal in the iron tailings has reached the recovery peak value.

[0041] Preferably, the water washing temperature in step S3 is greater than or equal to 20℃.

[0042] When the water washing temperature is too low, the heavy metal chloride dissolves too slowly, affecting the leaching rate of heavy metals; when the water washing temperature is too high, the cost is high and it is not easy to operate.

[0043] More preferably, the water washing temperature in step S3 is 20-90℃, further, the water washing temperature is room temperature, and more further, the room temperature is 25℃.

[0044] Preferably, the water washing time in step S3 is ≥20min, further, the water washing time is 20-120min.

[0045] When the water washing time is too short, the heavy metal chloride has not completely dissolved in water, and the leaching rate of heavy metals is less than 80%; when the water washing time is too long, the economy of the entire chlorination roasting reaction is not good, and when the water washing time is 120min, the peak value of water leaching of heavy metal chloride has been reached.

[0046] More preferably, the water washing time in step S3 is 20-90min, further, the water washing time is 60min.

[0047] Compared with the prior art, the present application has the following beneficial effects:

[0048] Compared with the existing chlorination roasting technology, the present application uses a composite chlorination agent, i.e. the alkaline etching powder obtained after drying the alkaline etching waste liquid, which has a significant improvement in recovery efficiency compared with single NH4Cl chlorination agent. Not only the heavy metals with toxic properties in the iron tailings are recovered, but also the copper resources in the alkaline etching waste liquid are recovered, among which the recovery rates of Pb, Zn and Mn in the iron tailings are all higher than 80%, which can reach 89.1%, 90.4% and 89.56% respectively, and the total Cu recovery rate of the iron tailings and the alkaline etching waste liquid is 99.4%, realizing the clean production goal of waste treatment with waste. DETAILED DESCRIPTION

[0049] The present application will be further described below in combination with specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field, and the reagents and materials used in the following examples are all commercially available.

[0050] Example 1

[0051] A method for recovering heavy metals by co-roasting iron tailings and alkaline etching powder, comprising the following steps:

[0052] S1, drying the alkaline etching waste liquid to obtain alkaline etching powder;

[0053] S2, mixing the dried iron tailings and alkaline etching powder and performing chlorination roasting;

[0054] S3, cooling the mixture obtained after roasting, water washing and recovering heavy metals;

[0055] The mass ratio of the iron tailings to the alkaline etching powder in step S2 is 1:0.05; the chlorination roasting temperature is 500 DEG C; and the chlorination roasting time is 30 min;

[0056] The solid-liquid ratio of water washing in step S3 is 1:10; and the water washing time is 60 min;

[0057] In step S1, the concentration of chloride ions in the alkaline etching waste liquid is 120 g / L; and the drying condition of the alkaline etching waste liquid is drying in an oven at 100 DEG C for 48 h;

[0058] In step S2, the contents of Pb, Zn, Cu and Mn in the iron tailings are 1.8 mg / g, 2 mg / g, 1.7 mg / g and 3.4 mg / g respectively; the drying condition of the iron tailings is drying in an oven at 105 DEG C for 24 h; and the iron tailings and the alkaline etching powder are crushed to pass through a 200-mesh screen;

[0059] In step S3, the water washing temperature is 25 DEG C.

[0060] Example 2

[0061] A method for recovering heavy metals by co-roasting iron tailings and alkaline etching powder, the steps being the same as in Example 1, except that the mass ratio of the iron tailings to the alkaline etching powder in step S2 is 1:0.03.

[0062] Example 3

[0063] A method for recovering heavy metals by co-roasting iron tailings and alkaline etching powder, the steps being the same as in Example 1, except that the mass ratio of the iron tailings to the alkaline etching powder in step S2 is 1:0.1.

[0064] Example 4

[0065] A method for recovering heavy metals by co-roasting iron tailings and alkaline etching powder, the steps being the same as in Example 1, except that the mass ratio of the iron tailings to the alkaline etching powder in step S2 is 1:0.3.

[0066] Example 5

[0067] A method for recovering heavy metals by co-roasting iron tailings and alkaline etching powder, the steps being the same as in Example 1, except that the chlorination roasting temperature in step S2 is 400 DEG C.

[0068] Example 6

[0069] A method for recovering heavy metals by co-roasting iron tailings and alkaline etching powder, the steps being the same as in Example 1, except that the chlorination roasting temperature in step S2 is 600 DEG C.

[0070] Example 7

[0071] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the chloridizing roasting temperature in step S2 is 800℃.

[0072] Example 8

[0073] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the chloridizing roasting time in step S2 is 20min.

[0074] Example 9

[0075] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the chloridizing roasting time in step S2 is 50min.

[0076] Example 10

[0077] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the chloridizing roasting time in step S2 is 120min.

[0078] Example 11

[0079] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the solid-liquid ratio of water washing in step S3 is 1:1.

[0080] Example 12

[0081] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the solid-liquid ratio of water washing in step S3 is 1:5.

[0082] Example 13

[0083] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the solid-liquid ratio of water washing in step S3 is 1:50.

[0084] Example 14

[0085] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the water washing temperature in step S3 is 90℃.

[0086] Example 15

[0087] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the water washing time in step S3 is 20min.

[0088] Example 16

[0089] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the water washing time in step S3 is 120 min.

[0090] Example 17

[0091] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the mass ratio of iron tailings to alkaline etching waste liquid powder in step S2 is 1:1; the chlorination roasting time is 200 min.

[0092] Example 18

[0093] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the solid-liquid ratio of water washing in step S3 is 1:100; the water washing temperature is 100℃; the water washing time is 180 min.

[0094] Comparative example 1

[0095] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the iron tailings in step S2 are replaced by Fe2O3.

[0096] Comparative example 2

[0097] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the alkaline etching waste liquid in step S1 is replaced by ammonium chloride.

[0098] Comparative example 3

[0099] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that no alkaline etching powder is added.

[0100] Comparative example 4

[0101] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the mass ratio of iron tailings to alkaline etching waste liquid powder in step S2 is 1:0.01.

[0102] Comparative example 5

[0103] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the chlorination roasting temperature in step S2 is 200℃.

[0104] Comparative example 6

[0105] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as example 1, the difference is that the chlorination roasting temperature in step S2 is 1000℃.

[0106] Comparative Example 7

[0107] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as Example 1, the difference is that the chlorination roasting time in step S2 is 5 min.

[0108] Comparative Example 8

[0109] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as Example 1, the difference is that the water washing solid-liquid ratio in step S3 is 1:0.5.

[0110] Comparative Example 9

[0111] A method for recovering heavy metals by co-roasting iron tailings with alkaline etching powder, the steps are the same as Example 1, the difference is that the water washing time in step S3 is 5 min.

[0112] Performance determination of test examples

[0113] The washing liquid obtained by each of the above examples and comparative examples was subjected to Pb, Zn, Cu, and Mn content determination by a flame atomic absorption spectrometer.

[0114] The calculation method of Pb, Zn, Cu, and Mn recovery rate is as follows:

[0115]

[0116] m1 and m2 respectively represent the mass of Pb, Zn, Cu, and Mn in the washing liquid and the mass of Pb, Zn, Cu, and Mn in the roasted ore.

[0117] The results are shown in Table 1.

[0118] Table 1. Heavy metal recovery rate / %

[0119] Pb Zn Cu Mn Example 1 88.5 88.3 98.2 89.0 Example 2 82.3 85.3 99.4 83.4 Example 3 87.9 88.2 99.3 87.4 Example 4 87.3 88.4 97.4 87.8 Example 5 83.2 84.3 98.3 80.3 Example 6 82.3 81.3 99.4 82.4 Example 7 89.7 88.0 96.3 87.6 Example 8 85.3 80.4 90.3 84.3 Example 9 88.3 90.4 99.3 89.4 Example 10 88.4 89.5 99.4 88.4 Example 11 82.1 84.3 96.3 88.3 Example 12 86.5 87.2 88.6 87.4 Example 13 88.6 89.4 97.4 88.0 Example 14 89.1 88.8 89.2 88.1 Example 15 83.4 82.4 93.5 86.4 Example 16 87.7 83.6 98.4 89.5 Example 17 85.2 86.4 93.4 88.4 Example 18 88.3 89.1 98.3 89.1 Comparative Example 1 0 0 99.2 0 Comparative Example 2 78.3 77.4 40.3 69.4 Comparative Example 3 1.2 3.4 5.4 0.84 Comparative Example 4 43.8 35.0 99.2 68.0 Comparative Example 5 23.0 31.0 97.0 13.0 Comparative Example 6 34.0 52.0 12.0 43.0 Comparative Example 7 58.9 47.8 88.7 57.9 Comparative Example 8 42.4 31.4 65.3 25.4 Comparative Example 9 67.4 57.5 84.2 69.3

[0120] In the above examples 1-18, by matching the mass ratio of iron tailings and alkali etching waste liquid powder, chlorination roasting temperature, and chlorination roasting time, the recovery rates of Pb, Zn, Cu, and Mn in the iron tailings all reach 80% or more, comprehensive treatment of the two wastes of iron tailings and alkali etching waste liquid is achieved, and the goal of clean production of waste treatment by waste is achieved. In Comparative Example 1, pure Fe2O3 is used to replace the iron tailings, and it is verified that by chlorination roasting, the recovery rate of Cu in the alkali etching waste liquid can reach 99.2%, compared with Example 1; in Comparative Example 2, pure NH4Cl is used as the chlorination roasting reducing agent, and the recovery rates of Pb, Zn, Cu, and Mn are 78.3%, 77.4%, 40.3%, and 69.4%, respectively, which shows that the use of alkali etching powder after drying of the alkali etching waste liquid can have higher heavy metal conversion efficiency than the use of pure NH4Cl as the chlorination agent; Comparative Example 3 shows that after chlorination roasting, the recovery rate of heavy metals in the iron tailings has been significantly improved; the data of Comparative Examples 4-9 show that when the mass ratio of iron tailings to alkali etching waste liquid powder, chlorination roasting temperature, chlorination roasting time, solid-liquid ratio of water washing, and water washing time are not within the range defined by the present application, although there is a certain heavy metal recovery effect, it cannot meet the requirement of the present application that the heavy metal recovery rate is more than 80%.

[0121] The present application not only recovers heavy metals in the iron tailings, but also has certain economic benefits in the harmless treatment of alkali etching waste liquid, and the collaborative treatment of iron tailings and alkali etching waste liquid achieves the goal of clean production of waste treatment by waste.

[0122] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not a limitation on the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. Here, it is not necessary and impossible to exhaust all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principles of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A method of recovering heavy metals by co-combusting iron tailings with alkaline etching dust, characterized by, The method comprises the following steps: S1, drying treatment of the alkaline etching waste liquid to obtain alkaline etching powder; S2, mixing the dried iron tailings and the alkaline etching powder and then performing chlorination roasting; S3, cooling and water washing the mixture obtained after the roasting to recover heavy metals; The mass ratio of the iron tailings to the alkaline etching powder in the step S2 is 1:0.03-0.3; the chlorination roasting temperature is 400-800 DEG C; and the chlorination roasting time is 20-120 min; The solid-liquid ratio in the water washing in the step S3 is 1:1-50; the water washing time is 20-120 min; and the components of the alkaline etching powder include copper ammonia complex, NH4Cl and NaCl.

2. The method of claim 1, wherein, The mass ratio of the iron tailings to the alkaline etching powder in the step S2 is 1:0.03-0.

1.

3. The method of claim 1, wherein, The chlorination roasting temperature in the step S2 is 400-600 DEG C.

4. The method of claim 1, wherein, The chlorination roasting time in the step S2 is 20-50 min.

5. The method of claim 1, wherein, The solid-liquid ratio in the water washing in the step S3 is 1:5-50.

6. The method of claim 1, wherein, The water washing temperature in the step S3 is 20-90 DEG C.

7. The method of claim 1, wherein, The water washing time in the step S3 is 20-90 min.

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