Method for treating acid leaching high-silicon slag through low-temperature alkaline roasting

Abstract

The invention belongs to the technical field of solid waste resource recycling, and provides a method for treating acid-leached high-silicon slag through low-temperature alkaline roasting, which comprises the following steps: (1) mixing the acid-leached high-silicon slag with an alkaline reagent, and carrying out alkaline roasting at low temperature of 600-900 DEG C; (2) performing water leaching on a product obtained by roasting in the step (1) to obtain a sodium silicate solution and water leaching residues; the acid leaching high-silicon slag is high-silicon slag generated by acid leaching during wet leaching of copper slag. According to the method, the acid-leached high-silicon slag reacts with the alkaline reagent, so that silicon exists in the roasted product in the form of sodium silicate, the silicon can be separated from other elements through water leaching, the purposes of transformation and separation are achieved, the silicon yield can reach 92% or above, and the technological process is short.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource recycling, and in particular relates to a method for treating acid-leached high-silicon slag by low-temperature alkaline roasting. Background Art

[0002] With the continuous development of economy and technology, the demand for refined copper is also increasing. However, a large amount of copper slag is produced in the process of copper matte blowing to produce refined copper. The copper slag is usually treated with acid leaching because the copper slag is mainly produced in the process of pyrometallurgical copper smelting and contains a large amount of valuable metals such as iron, copper, and zinc. Acid leaching can effectively recover valuable metals and improve resource utilization, which has economic value and technical feasibility.

[0003] Wet leaching is the mainstream process for treating copper slag at present, but a large amount of high-silicon slag will be produced after acid leaching in wet leaching. The storage of high-silicon slag occupies a large amount of land and will pollute the environment if not properly disposed of. With the further revision of the relevant policies on industrial solid waste treatment in the country, high-silicon slag has been included in the "National List of Hazardous Wastes". On the other hand, high-silicon slag consists of 60-80% SiO 2 As well as a small amount of Fe and Al oxides, it is a high-quality raw material for producing high-value silicon-based materials. Treating high-silicon slag as a silicon source not only solves the problem of high-silicon slag disposal, but also realizes the resource utilization of silicon. Therefore, the proper treatment of high-silicon slag is of great significance to the sustainable development of the copper smelting industry.

[0004] At present, there are few studies on the high-value comprehensive recycling of high-silicon slag as a silicon source. Most high-silicon slag is only used as building materials, concrete cement or slag-making agent, which cannot achieve high-value utilization of resources; a small part of high-silicon slag is used to produce high-value products, but the energy consumption is high and the process is long. For example, Chinese invention patent CN 110194655 A discloses a method for preparing building ceramsite using high-silicon tailings, and specifically discloses the following steps: extrusion molding, fluidized drying, screening, re-drying, firing, and cooling to obtain building ceramsite. Chinese invention patent CN 107973534 A discloses the use of high-silicon and low-crystallization siliceous raw materials in the production of cement clinker, and specifically discloses mixing the siliceous raw materials with other raw material ingredients, grinding them, and finally sending them into the cement kiln for calcining to obtain clinker. This type of method is simple and easy to operate, and realizes the harmlessness of high-silicon tailings, but the high-value utilization of high-silicon slag has not been studied in depth. Chinese invention patent CN 109292779 A discloses a method for producing high-purity silicon / silicon alloy by slag refining with high-silicon waste, and specifically discloses drying the high-silicon waste and using it as a slag-forming agent for slag refining. This method does not require excessive treatment of the high-silicon waste, is simple and direct, reduces the pollution of the waste to the environment, and realizes the recycling of the waste, but the use of high-silicon waste is limited and cannot be processed on a large scale. Chinese invention patent CN 110980753 B discloses a process for producing high-quality sodium silicate using high-silicon iron ore, specifically disclosing the following steps: 1) making reducing materials: making high-silicon iron ore into pellets to be sintered; 2) reducing the pellets to be sintered: heating the pellets to be sintered at high temperature to obtain reduced pellets; 3) crushing and grinding high-silicon tailings: crushing and reducing the pellets to obtain reduced crushed materials, using an ultrafine grinding device to grind and select the reduced crushed materials to obtain reduced powder, and magnetically selecting the reduced powder to obtain high-silicon tailings; 4) extracting sodium silicate solution: adding alkali solution to the high-silicon tailings to obtain a solid-liquid mixture, and leaching sodium silicate solution. This method realizes the high-value utilization of high-silicon slag, but the energy consumption is high and the process is long.

[0005] Therefore, it is necessary to develop a high-value recovery method with mild conditions, low energy consumption, and the ability to process high-silicon slag in large quantities. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the existing technology cannot realize the large-scale and high-value utilization of high-silicon slag, overcomes the shortcomings and defects mentioned in the above background technology, and provides a method for low-temperature alkaline roasting treatment of acid leaching high-silicon slag.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0008] A method for treating acid-leached high-silicon slag by low-temperature alkaline roasting, comprising the following steps:

[0009] (1) mixing the acid-leached high-silicon slag with an alkaline reagent and performing alkaline roasting at a low temperature, wherein the alkaline roasting temperature is 600 to 900° C.;

[0010] (2) leaching the product obtained by roasting in step (1) to obtain a sodium silicate solution and leaching residue;

[0011] The acid leached high silicon slag is the high silicon slag produced by acid leaching when wet leaching copper slag.

[0012] The copper smelting process produces copper slag, which contains about 5wt% Cu and a small amount of Pb and Zn. The copper slag is leached with strong acid to obtain acid-leached silicon slag (SiO 2 10wt%), the acid-leached silicon slag is washed with water to obtain acid-leached high silicon slag (SiO 2 60-80wt%). The high silicon slag produced by acid leaching during wet leaching of copper slag contains a large amount of silicon dioxide. In order to fully recover silicon, the silicon is subjected to alkaline roasting and transformation treatment, and separated by water leaching. This method has low energy consumption and simple operation, and is of great help to the high-value utilization of silicon.

[0013] In addition to containing a large amount of silicon dioxide, the high-silicon slag produced by acid leaching during wet leaching of copper slag may also contain a large amount of iron oxides and compounds of other metal elements such as copper. The metal element composition is relatively complex and usually requires transformation at 800℃-1200℃ or even higher. The alkaline roasting scheme can simultaneously achieve the transformation and recovery of the above-mentioned transition metal elements; alkaline roasting also avoids the generation of alkaline wastewater and reduces energy consumption to a certain extent.

[0014] In the present invention, the acid-leached high-silicon slag is subjected to alkaline roasting with an alkaline reagent to transform the silicon into a sodium silicate phase. According to the different water solubility of the roasted product, the roasted product is then water-leached to achieve silicon separation. The main chemical reactions that occur during the alkaline roasting process are as follows:

[0015] 8SiO 2 +3Na 2 CO 3 =Na 6 Si 8 O 19 +3CO 2 (g)

[0016] 2SiO 2 +Na 2 CO 3 =Na 2 Si 2 O 5 +CO 2 (g)

[0017] SiO 2 +Na 2 CO3 =Na 2 SiO3+CO 2 (g)

[0018] 2SiO 2 +3Na 2 CO 3 =Na 6 Si 2 O 7 +3CO 2 (g)

[0019] SiO 2 +2Na 2 CO 3 =Na 4 SiO 4 +2CO 2 (g)

[0020] FeO+Na 2 CO 3 =Na 2 FeO 2 +CO 2 (g)

[0021] Fe 2 O 3 +Na 2 CO 3 =2NaFeO 2 +CO 2 (g)

[0022] Al 2 O 3 +2SiO 2 +Na 2 CO 3 =2NaAlSiO 4 +CO 2 (g)

[0023] During the alkaline roasting process, only a small amount of CO 2 It will not pollute the environment, and the silicon in the calcined product exists in the form of sodium silicate, which is easily soluble in water, while the impurity aluminum exists in the form of sodium aluminosilicate, which is insoluble in water. It can be separated by simple water leaching and filtration. The impurity iron mainly exists in the form of sodium ferrite. The iron precipitate can be obtained by controlling the pH later, and it can be removed by filtering together with sodium aluminate. When the alkaline calcination temperature is 500°C, the calcined product is immersed in water, and there is still a relatively obvious silicon dioxide phase peak in the slag, indicating that the temperature conditions required for the calcination transformation have not been reached at this time, and the transformation effect is poor (see Figure 2 When the alkaline roasting temperature is 750℃, the XRD spectrum of the water-leached slag shows a diffuse peak (see Figure 2), the sodium silicate phase peak completely disappears, indicating that the water leaching process can ensure that the generated sodium silicate enters the solution. Therefore, the temperature of the alkaline roasting in this application is 600-900°C; if the roasting temperature is too low or too high, the roasting product contains untransformed silicon dioxide and a molten phase formed at high temperature, which affects the recovery rate of silicon and is not conducive to subsequent water leaching operations.

[0024] Preferably, the alkaline agent comprises Na 2 CO 3 、NaHCO 3 , NaOH, KOH, K 2 CO 3 or KHCO 3 One or more of .

[0025] More preferably, the alkaline agent is Na 2 CO 3 .

[0026] Choose Na 2 CO 3 The cost is low, and as can be seen from the reaction equation below, its utilization rate is also higher.

[0027] SiO 2 +Na 2 CO 3 =Na 2 SiO 3 +CO 2 (g)

[0028] SiO 2 +2NaHCO 3 =Na 2 SiO 3 +2CO 2 (g)+H 2 O

[0029] SiO 2 +2NaOH=Na 2 SiO 3 +H 2 O

[0030] Preferably, the mass ratio of the acid leaching high silicon slag to the alkaline reagent is 1:(0.6-3). The mass ratio of the acid leaching high silicon slag to the alkaline reagent needs to be controlled within the preferred range of the present invention. If the amount of the alkaline reagent is too much, the raw material cost will increase; if the amount of the alkaline reagent is too little, it is difficult to achieve the conversion of silicon into sodium silicate, thereby affecting the recovery rate of silicon.

[0031] Preferably, the alkaline calcination time is 30 to 240 minutes. The alkaline calcination time within this range can ensure a thorough reaction. If the calcination time is too long, energy consumption will increase, and if the calcination time is too short, the reaction will not be thorough. The calcination temperature and calcination time of the present invention can achieve the transformation of silicon dioxide, and the operation is simple and the conditions are easy to control.

[0032] Preferably, during the water immersion process, the water immersion temperature is 30 to 90° C., the liquid-to-solid ratio is 3 to 20 mL:1 g, and the leaching time is 30 to 180 min.

[0033] Preferably, the acid leaching high silicon slag mainly comprises SiO 2 60-80wt%, Fe 3-10wt%, Al 1-10wt%.

[0034] Preferably, after the water immersion in step (2), the pH of the solution after water immersion is adjusted to 8.9-9.6, and after the precipitation is formed, the sodium silicate solution and water immersion residue are obtained by filtering.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention utilizes acid leaching of high-silicon slag to react with an alkaline reagent, so that silicon exists in the form of sodium silicate in the roasted product, so that silicon can be separated from other elements by water leaching, thereby achieving the purpose of transformation and separation, and the silicon yield can reach more than 92%, and the process flow is short;

[0037] (2) The present invention treats acid leached high-silicon slag through alkaline roasting, which is simple to operate and has low energy consumption. It only needs to calculate the amount of materials to be mixed and roasted to complete the process. It is easy to realize automation and is suitable for industrial application. It overcomes the problems of long process, high energy consumption, small processing volume and insufficient high-value utilization in traditional treatment of high-silicon slag.

[0038] In summary, the method of recovering silicon by acid leaching high-silicon slag and adding alkaline reagents for alkaline roasting of the present invention can achieve efficient extraction of silicon with a short process, eliminating the problems of long process, high energy consumption, small processing volume and insufficient high-value utilization existing in the traditional treatment of high-silicon slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 The present invention is a process flow chart of low temperature alkaline roasting treatment of acid leaching high silicon slag.

[0041] Figure 2 The XRD spectra of the acid-leached high-silicon slag calcined at 500°C and 750°C and the water-leached slag of Example 1 and Comparative Example 1 of the present invention are shown. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0043] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0045] The acid-leached high-silicon slag treated in the following examples is obtained from the copper slag obtained from the pyrometallurgical copper smelting process of Jilin Zijin Mining Co., Ltd. after acid leaching and water washing. The specific chemical composition is: SiO 2 78.54wt%, Fe 3.08wt%, Al 1.04wt%; the content of Cu, Pb and Zn elements are 0.049wt%, 0.091wt% and 0.028wt% respectively, and their influence on alkaline roasting can be ignored.

[0046] After the acid-leached high-silicon slag after copper selection is washed with water, the washing liquid is acidic. The substance obtained by evaporating the washing liquid is analyzed by XRD test and the composition is FeSO 4 There is generally no sulfate in copper slag, which indicates that the FeSO2 remaining when the copper slag is leached with sulfuric acid is 4 , that is, this silicon slag is obtained by acid leaching.

[0047] Embodiment 1:

[0048] A method for treating acid leaching high silicon slag by low temperature alkaline roasting of the present invention, the process flow chart of which is as follows Figure 1 As shown, the specific steps include:

[0049] (1) Accurately weigh 10g of acid leaching high silicon slag and alkaline reagent Na 2 CO 3 20g, mix thoroughly and put into a ceramic crucible;

[0050] The ceramic crucible is placed in a muffle furnace for alkaline calcination. The calcination process is carried out in an air atmosphere. The alkaline calcination temperature is controlled to be 750°C for 120 minutes. After the calcination reaction is completed, the crucible is cooled to room temperature with the furnace.

[0051] (2) Take out 5 g of the calcined product and soak it in water once. The immersion temperature is 70°C, the liquid-to-solid ratio is 10 mL:1 g, and the time is 1 h. After filtration, 250 mL of sodium silicate solution (silicon concentration is 5.11 g / L) and 0.31 g of leached residue are obtained.

[0052] Figure 2 These are the XRD spectra of the acid-leached high-silicon slag calcined at 750°C and the water-leached product of this example.

[0053] Calculate the water leaching dissolution rate and silicon leaching rate of the roasted product. The water leaching dissolution rate refers to the mass loss rate of the roasted product before and after water leaching, that is, the ratio of the soluble target substance dissolved in the solution to the mass of the roasted product.

[0054] The silicon leaching rate refers to the ratio of the mass of silicon element calculated based on the volume and concentration of the water leaching solution to the total mass of silicon in the roasted raw material (acid leaching high silicon slag).

[0055] According to the test, the water leaching solubility of the roasted product is 93.80%, and the silicon leaching rate after water leaching is 91.56%.

[0056] Embodiment 2:

[0057] A method for treating acid leaching high silicon slag by low temperature alkaline roasting of the present invention, the process flow chart of which is as follows Figure 1 As shown, the specific steps include:

[0058] (1) Accurately weigh 10g of acid leaching high silicon slag and alkaline reagent Na 2 CO 3 18g + NaOH 2g, a total of 20g, mix thoroughly and put into a ceramic crucible;

[0059] The ceramic crucible is placed in a muffle furnace for alkaline calcination. The calcination process is carried out in an air atmosphere. The alkaline calcination temperature is controlled to be 850°C for 120 minutes. After the calcination reaction is completed, the crucible is cooled to room temperature with the furnace.

[0060] (2) Take 5 g of the calcined product and soak it in water once. The water soaking temperature is 70°C, the liquid-to-solid ratio is 10 mL:1 g, and the time is 1 h. After filtration, 100 mL of sodium silicate solution (silicon concentration is 9.20 g / L) and 0.43 g of water-leached residue are obtained.

[0061] According to the test, the water leaching solubility of the roasted product is 91.40%, and the silicon leaching rate after water leaching is 90.52%.

[0062] Comparative Example 1:

[0063] The method for treating acid leaching high silicon slag by low temperature alkaline roasting in this comparative example comprises the following steps:

[0064] (1) Accurately weigh 10g of acid leaching high silicon slag and alkaline reagent Na 2 CO 3 20g, mix thoroughly and put into a ceramic crucible;

[0065] (2) placing the ceramic crucible in a muffle furnace for alkaline calcination. The calcination process is carried out in an air atmosphere. The alkaline calcination temperature is controlled to be 500° C. for 120 min. After the calcination reaction is completed, the crucible is cooled to room temperature in the furnace.

[0066] (3) Take 5 g of the calcined product and soak it in water once. The water soaking temperature is 70°C, the liquid-to-solid ratio is 10 mL:1 g, and the time is 1 h. After filtration, 100 mL of sodium silicate solution (silicon concentration is 6.67 g / L) and 2.31 g of water-leached residue are obtained. Figure 2 This is the XRD spectrum of the acid leached high silicon slag calcined at 500°C and the water leached product in this comparative example.

[0067] Comparing the XRD patterns of the products calcined at 500℃ and 750℃ and water leaching, it can be clearly seen that at 500℃, some SiO2 that did not participate in the reaction still exists in the calcined products. 2 and Na 2 CO 3 Phase peak, there is also insoluble SiO in the water leaching product 2 , indicating that SiO 2 The temperature required for complete transformation. The calcined product at 750℃ is mainly Na 2 SiO 3 There are no phase peaks and no impurity peaks, which shows that the transformation effect is better at this time, and the XRD spectrum of the water-immersion product is consistent with it.

[0068] According to the test, the water leaching solubility of the roasted product was 53.80%, and the silicon leaching rate after water leaching was 54.29%.

[0069] Comparative Example 2:

[0070] The method for treating acid leaching high silicon slag by low temperature alkaline roasting in this comparative example comprises the following steps:

[0071] (1) Accurately weigh 10g of acid leaching high silicon slag and alkaline reagent Na 2 CO 3 10g, mix thoroughly and put into a ceramic crucible;

[0072] (2) placing the ceramic crucible in a muffle furnace for alkaline calcination. The calcination process is carried out in an air atmosphere. The alkaline calcination temperature is controlled to be 800° C. for 120 min. After the calcination reaction is completed, the crucible is cooled to room temperature in the furnace.

[0073] (3) Take 5 g of the calcined product and soak it in water once. The immersion temperature is 70°C, the liquid-to-solid ratio is 10 mL:1 g, and the time is 1 h. After filtration, 100 mL of sodium silicate solution (silicon concentration is 5.85 g / L) and 2.51 g of leached residue are obtained.

[0074] According to the test, the water leaching solubility of the roasted product is 49.80%, and the silicon leaching rate after water leaching is 47.65%.

Claims

1. A method for treating acid-leached high-silicon slag by low-temperature alkaline roasting, characterized in that: The following steps are involved: (1) mixing acid leached high silicon slag with an alkaline reagent, wherein the mass ratio of the acid leached high silicon slag to the alkaline reagent is 1:1.2-3; performing alkaline roasting at a low temperature, wherein the temperature of the alkaline roasting is 600-900°C; (2) leaching the product obtained by roasting in step (1) to obtain a sodium silicate solution and leaching residue; The acid leached high silicon slag is the high silicon slag produced by acid leaching when wet leaching copper slag.

2. The method according to claim 1, characterized in that The alkaline reagent includes one or more of Na2CO3, NaHCO3, NaOH, KOH, K2CO3 or KHCO3.

3. The method according to claim 1, characterized in that The alkaline roasting time is 30 min to 240 min.

4. The method according to claim 1, characterized in that During the water immersion process, the water immersion temperature is 30-90° C., the liquid-to-solid ratio is 3-20 mL:1 g, and the leaching time is 30-180 min.

5. The method according to claim 1, characterized in that The acid leaching high silicon slag mainly comprises SiO2 60-80wt%, Fe 3-10wt%, and Al 1-10wt%.

6. The method according to claim 5, characterized in that After the water immersion in step (2), the pH of the solution after water immersion is adjusted to 8.9-9.6, and after the precipitation is formed, the sodium silicate solution and water immersion residue are obtained by filtering.

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