Method for whole detoxification of cyanide tailings secondary aluminum dross and preparation of cementitious material

Abstract

The present application belongs to the field of resource comprehensive utilization and environmental protection treatment technology, and relates to a method for whole detoxification of cyanide tailings and secondary aluminum ash and preparation of cementing material. The method comprises the following steps: carrying out partial de-cyanation treatment on the cyanide tailings by using sulfur dioxide tail gas through the Inco process to obtain de-cyanation tailings; mixing the de-cyanation tailings with desulfurization gypsum, secondary aluminum ash and correction material, and then calcining to obtain a sulphoaluminate cement clinker and the sulfur dioxide tail gas. The method can not only realize whole detoxification of cyanide tailings and secondary aluminum ash, but also prepare cementing material, and can recover precious metals in the cyanide tailings, so as to realize the development of cyanide tailings and secondary aluminum ash into harmless, large-scale and resource-based path.

Description

Technical Field

[0001] This invention belongs to the field of resource comprehensive utilization and environmental protection and governance technology, and relates to a method for the overall detoxification of cyanide tailings and the synergistic preparation of cementitious materials. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] The cyanide gold extraction process generates large quantities of cyanide tailings from flotation gold concentrate and whole-sludge cyanide tailings during gold production. The large stockpiles of cyanide tailings contain undecomposed cyanides and heavy metals, severely polluting water and soil. Acidification is commonly used to remove cyanide from the flotation cyanide tailings, followed by the recovery of gold, copper, lead, sulfur, etc. However, this process generates highly toxic hydrogen cyanide, posing serious safety hazards.

[0004] In the electrolytic aluminum process, slag is formed when the molten aluminum is smelted in the furnace, known as primary aluminum ash. The residue left after extracting metallic aluminum from primary aluminum ash or other waste aluminum using physical or chemical methods is called secondary aluminum ash. Secondary aluminum ash is mainly treated by water washing or pyrometallurgical calcination and used to synthesize polyaluminum chloride, calcium aluminate water purifiers, ceramics, etc. However, the wastewater generated by water washing is difficult to treat further; in pyrometallurgical calcination, the high chloride content in secondary aluminum ash can cause kiln tail adhesion during calcination, making it difficult for the calcination equipment to operate stably and long-term, and also difficult to utilize harmlessly.

[0005] Currently, there are recycling methods that utilize cyanide tailings and secondary aluminum ash to produce cementitious materials, but these methods require a large amount of other auxiliary materials, resulting in high economic and operating costs, making them difficult to promote. Summary of the Invention

[0006] To address the lack of solutions for the synergistic utilization of cyanide tailings and secondary aluminum ash in existing technologies, the present invention aims to provide a method for the overall detoxification of cyanide tailings and secondary aluminum ash and the synergistic preparation of cementitious materials. This method not only achieves overall detoxification of cyanide tailings and secondary aluminum ash and the preparation of cementitious materials, but also recovers precious metals from the cyanide tailings, thereby enabling the development of cyanide tailings and secondary aluminum ash towards a harmless, large-scale, and resource-oriented path.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] On the one hand, a method for the overall detoxification of cyanide tailings and the synergistic preparation of cementitious materials through secondary aluminum ash removal includes the following steps:

[0009] Using sulfur dioxide tail gas, partial decyanation treatment of cyanide tailings was carried out through the Inco process to obtain decyanated tailings.

[0010] The cyanide tailings are mixed with desulfurization gypsum, secondary aluminum ash, and correction material, and then calcined to obtain sulfoaluminate cementitious clinker and the sulfur dioxide tail gas.

[0011] This invention aims to prepare a gelling material from cyanide tailings. The main obstacle to its formation as a gel lies in its high concentration of cyanide ions and precious metals. Direct extraction of the precious metals first easily produces highly toxic hydrogen cyanide. Therefore, this invention uses cyanide tailings and secondary aluminum ash in combination. The secondary aluminum ash contains a large amount of chlorides (such as NaCl and KCl). During calcination, the precious metals in the cyanide tailings can combine with the chlorides in the secondary aluminum ash to form precious metal chlorides, which can be discharged with the flue gas. However, due to its high concentration of cyanide ions, its practical application is limited.

[0012] The Inco process utilizes sulfur dioxide and air to oxidize cyanide under the catalysis of copper, thereby achieving cyanide removal. This invention employs the Inco process to treat cyanide removal tailings, where sulfur dioxide can be generated during the decomposition of desulfurized gypsum as a calcium source in the preparation of cementitious materials. However, current Inco processes use pure sulfur dioxide and air to oxidize cyanide. While this invention generates sulfur dioxide, it is present in the flue gas. Extracting sulfur dioxide from the flue gas would complicate the process and increase costs. Furthermore, this invention uses sulfur dioxide tail gas instead of sulfur dioxide, making complete cyanide removal difficult.

[0013] However, through research, this invention unexpectedly discovered that although using sulfur dioxide tail gas instead of sulfur dioxide in the Inco process is insufficient to completely remove cyanide from cyanide tailings, it can remove some of the cyanide, significantly reducing its concentration. Furthermore, the remaining cyanide will complex with metals in the tailings, preventing the presence of cyanide ions in the water. Although the tailings still contain cyanide complexed with metals, the concentration is low, and it is removed through calcination during the preparation of the cementitious material. Thus, this invention achieves overall detoxification of secondary aluminum ash from cyanide tailings, simultaneously preparing sulfoaluminate cementitious materials. Moreover, since precious metals combine with the chlorine in the secondary aluminum ash to form chlorides of precious metals, which are then discharged with the flue gas, precious metal recovery is also possible.

[0014] On the other hand, a system for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings secondary aluminum ash, used to achieve the above method, includes:

[0015] The Inco process decyanation reactor is used to partially decyanate sulfur dioxide tail gas by using the Inco process to treat cyanide tailings, producing decyanated tailings.

[0016] The mixing and calcining device is used to mix the decyanation tailings from the Incorea decyanation reactor with desulfurization gypsum, secondary aluminum ash, and corrective material, and then calcine them to produce sulfoaluminate cementitious clinker and sulfur dioxide tail gas, and then transport the sulfur dioxide tail gas to the Incorea decyanation reactor.

[0017] The beneficial effects of this invention are as follows:

[0018] (1) The method provided by the present invention can utilize a large amount of cyanide tailings and secondary aluminum ash to prepare sulfoaluminate special cementitious materials and recover gold and silver at the same time. It can not only solve the disadvantage of high raw material cost of sulfoaluminate cementitious materials, but also make extensive use of industrial solid waste and reduce the large amount of carbon dioxide emissions, reduce the greenhouse effect, and recover a large amount of gold and silver from cyanide tailings, thereby reducing the production cost of recovering gold and silver from cyanide tailings.

[0019] (2) The sulfoaluminate special cementitious material prepared by the method provided by the present invention is composed of calcium, aluminum, silicon, sulfur, magnesium, etc., while gold and silver precious metals are mainly formed by the chloride contained in secondary aluminum ash and the high-temperature chlorination and calcination of cyanide tailings to form dust flue gas containing precious metals. It is suitable for production using solid waste with high sulfur, magnesium and aluminum content as raw materials. At the same time, the flue gas containing SO2 is compressed and pumped into the cyanide tailings slurry to achieve partial removal of cyanide in the cyanide tailings, and further removal through calcination. The sulfoaluminate cementitious material has excellent properties such as early strength, high strength, wear resistance and negative temperature construction. While effectively improving the added value of cyanide tailings and secondary aluminum ash, it realizes the harmless utilization of hazardous wastes such as cyanide tailings and secondary aluminum ash, and the sulfoaluminate special cementitious material prepared can recover gold, silver and other precious metals.

[0020] (3) This invention pre-treats cyanide tailings by oxidation and decyanation using the Inco process. Then, it uses the decyanation tailings (after pre-treatment), secondary aluminum ash, and desulfurized gypsum as the main raw materials to directly obtain sulfoaluminate special cementitious materials and recover gold and silver through processes such as matching, drying, grinding, and calcination. This can realize the development of cyanide tailings, secondary aluminum ash, and desulfurized gypsum towards a harmless, large-scale, and resource-based path.

[0021] (4) The present invention utilizes cyanide tailings, secondary aluminum ash, and desulfurized gypsum to produce sulfoaluminate cementitious materials to recover gold and silver. The raw materials for preparing sulfoaluminate cementitious materials mainly come from cyanide tailings for gold extraction, secondary aluminum ash produced by electrolytic aluminum plants, and desulfurized gypsum produced by thermal power plants. The raw materials are entirely derived from general solid waste and hazardous waste generated by the chemical, mining, power and metallurgical industries, and the raw materials are widely available. This process can utilize industrial solid waste and hazardous waste on a large scale, while simultaneously producing sulfoaluminate cementitious materials. These materials possess characteristics such as early strength, high strength, ability to be constructed at sub-zero temperatures, and good wear resistance. They can be applied in applications such as undersea tunnels, Antarctic research stations, rapid road repair sections, and military engineering. During the production of sulfoaluminate cementitious materials, the flue gas from the cement rotary kiln contains dust that can be used to recover precious metals such as gold and silver. At the same time, due to the partial decomposition of desulfurized gypsum, the sulfur dioxide produced works in conjunction with air to oxidize and remove cyanide from the cyanide tailings. The cyanide tailings after cyanide removal can provide the main components such as Ca, Si, and Al required for the production of sulfoaluminate cementitious materials.

[0022] (5) The method of the present invention is different from the previous comprehensive utilization of general solid waste and hazardous waste such as cyanide tailings, secondary aluminum ash, and desulfurization gypsum. In the process of preparing sulfoaluminate cementitious materials, the flue gas containing gold and silver dust is used to recover precious metals gold and silver, respectively. At the same time, the flue gas contains a large amount of SO2 for partial removal of cyanide from cyanide tailings. The chlorides such as NaCl and KCl contained in secondary aluminum ash can be used as chlorinating agents in the chlorination and calcination process of cyanide tailings. The mineral composition of the sulfoaluminate cementitious material is different from that of conventional sulfoaluminate cement. Although it is mainly composed of 3CaO·3Al2O3·CaSO4, it also contains MgAl2O4 mineral phase introduced and newly generated due to the use of secondary aluminum ash, as well as a small amount of free MgO. It is a special cementitious material that is resistant to high temperature and corrosion. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 This is a process flow diagram in an embodiment of the present invention;

[0025] Figure 2 The XRD results are for the sulfoaluminate cementitious material prepared in Example 1. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] The reagents and raw materials used in this invention can all be purchased through conventional channels. Unless otherwise specified, the reagents and raw materials used in this invention shall be used in accordance with conventional methods in the art or according to the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] Currently, there is no technology that can utilize solid waste and hazardous waste such as cyanide tailings, secondary aluminum ash, and desulfurization gypsum to jointly prepare sulfoaluminate cementitious materials and recover gold and silver precious metals, and achieve the harmless utilization of cyanide tailings and secondary aluminum ash. In order to solve the above problems, this invention provides a method for the overall detoxification of cyanide tailings and secondary aluminum ash to synergistically prepare cementitious materials.

[0030] A typical embodiment of the present invention provides a method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash, comprising the following steps:

[0031] Using sulfur dioxide tail gas, partial decyanation treatment of cyanide tailings was carried out through the Inco process to obtain decyanated tailings.

[0032] The cyanide tailings are mixed with desulfurization gypsum, secondary aluminum ash, and correction material, and then calcined to obtain sulfoaluminate cementitious clinker and the sulfur dioxide tail gas.

[0033] The chlorides in the secondary aluminum ash from the raw materials, along with the gold and silver from the matched raw materials, are calcined at high temperatures to obtain flue gas rich in metal chlorides. The chlorides volatilize and are captured by condensation in a cooler, yielding primary dust containing precious metals. Simultaneously, the aluminum nitride in the secondary aluminum ash is converted into alumina. The flue gas, after dust removal, is sent to a cyanide tailings decyanation device. After calcination, the matched raw materials achieve denitrification and desalination of the secondary aluminum ash, resulting in a clinker salt content of less than 1%.

[0034] The sulfoaluminate cementitious material clinker prepared by this invention has 3CaO·3Al2O3·CaSO4 and 2CaO·SiO2 as the main mineral phases, with the main mineral components accounting for 75-85%. The proportions of iron phase, MgAl2O4, and calcium silicate Ca3MgSi2O8 are 5-12%, 3-5%, and 0-3%, respectively. Furthermore, the specific surface area of ​​the sulfoaluminate cementitious material is 320-350 m² / g. 2 / g, with over 96% of the particles having a size of less than 300 mesh.

[0035] In some embodiments, the partial cyanide removal process involves passing sulfur dioxide tail gas into a cyanide tailings slurry containing a copper ion catalyst for treatment. Specifically, the process involves feeding the cyanide tailings into an aerated water-soluble tank. The water in the tank is industrial water containing a soluble copper catalyst (e.g., copper sulfate). The cyanide tailings, soluble copper catalyst, and industrial water are thoroughly mixed to prepare a slurry for reaction. In a neutral to weakly alkaline solution, under the action of the soluble copper catalyst, sulfur dioxide tail gas and air are introduced. The synergistic effect of sulfur dioxide and air oxidizes the cyanide into less toxic cyanate ions, which are further oxidized into bicarbonate and ammonia. More specifically, the sulfur dioxide tail gas is compressed into compressed gas and then fed into the cyanide tailings slurry containing a copper ion catalyst. More specifically, the treated slurry is pressure filtered to obtain wet cyanide-removed tailings. The wet cyanide-removed tailings are then crushed and dried to obtain cyanide-removed tailings.

[0036] The sulfur dioxide tail gas described in this invention can be flue gas after calcination. However, since the flue gas after calcination contains not only sulfur dioxide but also precious metal chlorides, it is difficult to recover the precious metal chlorides if partial decyanation is performed directly. In some embodiments, the sulfur dioxide tail gas is obtained by washing and dust removal of the flue gas after calcination. After washing and dust removal, the precious metal chlorides can be removed, and the precious metals can be recovered through further refining of the precious metal chlorides.

[0037] In some embodiments, the weight ratio of decyanation tailings, desulfurization gypsum, secondary alumina ash, and corrective material is 16–25:30–55:18–25:7–13, preferably 18–21:48–53:21–24:7–8. This ratio helps to obtain sulfoaluminate cementitious materials with superior performance.

[0038] In some embodiments, a corrective agent is added when the cyanide tailings, desulfurization gypsum, and secondary alumina ash are mixed. The corrective agent includes chlorides, aggregates, etc. The addition of chlorides ensures complete chlorination of precious metals in the cyanide tailings.

[0039] In some embodiments, a corrective agent is added to make the basicity coefficient of the mixed raw materials before calcination greater than 0.95 and the sulfur dioxide concentration in the flue gas exceed 20%; preferably, the corrective agent is added at a ratio of 7-8%.

[0040] In some embodiments, desulfurization gypsum and decyanation tailings wet residue (i.e., undried decyanation tailings) are dried together and then mixed with secondary aluminum ash.

[0041] In some embodiments, desulfurized gypsum, wet slag from decyanation tailings, and secondary aluminum ash are homogenized, mixed, and dried. The main components of the mixed and dried raw materials are CaSO4, SiO2, CaO, Al, Al2O3, Fe2O3, MgO, and AlN. The desulfurized gypsum contains two main minerals, calcium sulfite and calcium sulfate. Calcium sulfite decomposes at 600–650°C, forming CaO and sulfur dioxide. Calcium sulfate decomposes at 1000–1200°C. Thus, at a calcination kiln temperature of 1200–1300°C, some of the desulfurized gypsum will produce sufficient CaO. At this point, calcium oxide reacts with alumina and calcium sulfate to form calcium sulfoaluminate, while magnesium oxide and alumina readily form magnesium aluminum spinel.

[0042] In some embodiments, the calcination temperature is 1200–1300°C, preferably 1250–1280°C. At this temperature, the well-matched cyanide tailings, secondary aluminum ash, and desulfurized gypsum can ensure the formation of the 3CaO·3Al2O3·CaSO4 and 2CaO·SiO2 mineral phases.

[0043] In some embodiments, the calcination time is 40 to 70 minutes; preferably 40 minutes.

[0044] The above-mentioned method of the present invention can ensure that the main mineral phases in the calcined sulfoaluminate cementitious material are 3CaO·3Al2O3·CaSO4 and 2CaO·SiO2, while also containing a small amount of MgAl2O4. The combination of each component meets the requirements of sulfoaluminate cementitious materials for early strength and rapid hardening. It can also make the chlorides in the sulfur and aluminum ash of desulfurized gypsum harmless and resource-based, thereby enabling further reactions of SO2 with oxygen and cyanide, as well as the chlorination roasting of gold and silver with chlorides, making the recovery of gold and silver possible.

[0045] Using desulfurized gypsum to replace natural gypsum and limestone, and secondary aluminum ash to replace high-grade bauxite, however, the raw materials do not contain enough CaO and Al2O3 to directly generate 3CaO·3Al2O3·CaSO4. Specific secondary products are required before this mineral can be generated. The CaSO3 and CaSO4 in desulfurized gypsum can decompose into CaO and SO2 at 600-650℃ and 1000-1200℃, respectively. At the same time, in the process of dry calcination, the secondary aluminum ash mainly transforms aluminum nitride into Al2O3 and nitrogen. The main component of the calcined aluminum ash is Al2O3. Sodium chloride and potassium chloride salts directly react with precious metals in cyanide tailings to form chloride dust. The dust contains a large amount of SO2 flue gas. At this time, the system has the main raw materials and functions of 3CaO·3Al2O3·CaSO4 and 2CaO·SiO2, as well as a small amount of MgAl2O4 minerals, and co-producing flue gas rich in metal chlorides and SO2. However, the calcination temperature of the system requires specific settings for the decomposition and calcination zones, as well as settings for dust removal from flue gas rich in metal chlorides and SO2 and reduction and decyanation of SO2 cyanide. If the settings are not accurate, it is difficult to form intermediate products CaO, SO2, and metal chloride-rich phases, and it is even more impossible to prepare special cementitious materials such as 3CaO·3Al2O3·CaSO4 and 2CaO·SiO2, MgAl2O4 to simultaneously recover precious metals and remove cyanide.

[0046] Therefore, how to use cyanide tailings, secondary aluminum ash, and desulfurized gypsum to prepare special cementitious materials with 3CaO·3Al2O3·CaSO4 and 2CaO·SiO2 as the main minerals, while generating a large amount of sulfur dioxide, is another problem that urgently needs to be solved.

[0047] Through investigation, this invention has found that when the weight ratio of cyanide tailings, desulfurized gypsum, secondary aluminum ash, and checker material (stone powder) is 16–25:30–55:18–25:7–13, the main temperature range for the oxidation of aluminum nitride to alumina is 800–1100℃. The decomposition temperatures of calcium sulfite and calcium sulfate in the desulfurized gypsum are 600–650℃ and 1000–1200℃, respectively, and the formation temperatures of calcium sulfoaluminate, dicalcium silicate, and magnesium aluminum spinel are 1200℃ and 1200℃, respectively. At temperatures ranging from ~1300℃, above 1100℃, and 900~1500℃, with a high-temperature holding period of 40 minutes, desulfurized gypsum, secondary aluminum ash, and cyanide tailings can be used to replace calcium oxide, calcium sulfate, and alumina to prepare special cementitious materials containing calcium sulfoaluminate, dicalcium silicate, and magnesium aluminum spinel. This process also provides a large amount of sulfur dioxide, which serves as a raw material for the removal of cyanide from cyanide tailings. Furthermore, it reduces energy consumption and raw material production costs, and improves the economic efficiency of recovering precious metals from cyanide gold extraction tailings.

[0048] In the material calcination stage, since secondary alumina ash, desulfurized gypsum, and cyanide tailings are used as raw materials, and bauxite, natural gypsum, alumina, calcium sulfate, and silicon dioxide used in limestone production are not used, no carbon dioxide decomposition is produced. Furthermore, the clinker minerals contain calcium sulfoaluminate, dicalcium silicate, iron phase, and magnesium aluminum spinel. The contents of 3CaO·3Al2O3·CaSO4, 2CaO·SiO2, iron phase, and MgAl2O4 mineral phases are 40–60%, 20–40%, and 5–10%, respectively. During production, a large amount of desulfurized gypsum can be utilized. After the sulfur in the desulfurized gypsum decomposes, SO2-containing dust is first formed. Further, under the action of a copper ion catalyst, it reacts with cyanide tailings to reduce cyanide to HCO3-, thus converting the cyanide in the cyanide tailings slurry into HCO3-. 3- NH 4+ Simultaneously, it can eliminate ferric cyanide complexes in the slurry; furthermore, sodium chloride and potassium chloride in the secondary aluminum ash combine with precious metals in the cyanide tailings during the calcination process to form flue gas dust containing precious metal chlorides; furthermore, during the calcination process, the residual cyanide is further removed through high-temperature sintering, thus realizing the purpose of using a large amount of desulfurized gypsum, secondary aluminum ash, and cyanide tailings to prepare sulfoaluminate special cementitious materials to recover precious metals, while simultaneously removing cyanide, which makes a significant contribution to digesting and storing cyanide tailings, desulfurized gypsum, and secondary aluminum ash.

[0049] Another embodiment of the present invention provides a system for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings secondary aluminum ash, used to implement the above method, comprising:

[0050] The Inco process decyanation reactor is used to partially decyanate sulfur dioxide tail gas by using the Inco process to treat cyanide tailings, producing decyanated tailings.

[0051] The mixing and calcining device is used to mix the decyanation tailings from the Incorea decyanation reactor with desulfurization gypsum, secondary aluminum ash, and corrective material, and then calcine them to produce sulfoaluminate cementitious clinker and sulfur dioxide tail gas, and then transport the sulfur dioxide tail gas to the Incorea decyanation reactor.

[0052] The Inco process decyanation reactor can be a decyanation tank for cyanide tailings slurry.

[0053] The mixing and calcining apparatus is, for example, a rotary kiln.

[0054] In some embodiments, a flue gas scrubbing device is included to remove precious metals from the calcined flue gas by chlorination to obtain sulfur dioxide tail gas, and then the sulfur dioxide tail gas is sent to the Inco decyanation reactor.

[0055] In some embodiments, a drying device is included for drying the wet residue of desulfurized gypsum and decyanation tailings produced by the Inco process.

[0056] In some embodiments, a surface-type waste heat recovery unit is included to provide the waste heat from the calcination flue gas generated by the mixing and calcining device as heat to the drying device. Specifically, the surface-type waste heat recovery unit utilizes the heat from the high-temperature solid-liquid mixture generated by the washing device through the calcination flue gas washing to dry and heat the raw material in the drying device, so that the total moisture content of the raw material is less than 2%, which facilitates subsequent grinding.

[0057] In some embodiments, a filter press is included for filtering the slurry produced after the reaction in the Inco decyanation reactor.

[0058] In some embodiments, a grinding mill is included for grinding the raw materials before calcination.

[0059] In some embodiments, a desulfurization tower is included for desulfurizing and venting the flue gas discharged from the Inco process decyanation reactor. This prevents sulfur dioxide from overflowing and polluting the environment.

[0060] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0061] Example 1

[0062] A method for the overall detoxification of cyanide tailings and the synergistic preparation of sulfoaluminate cementitious materials for the recovery of precious metals is as follows:

[0063] like Figure 1 As shown, the cyanide tailings (gold grade 3.64 g / t, gold particle size less than 10 μm) are first treated in a decyanation tank, where the cyanide inside is converted into HCO3- under the reduction of copper ion catalyst and SO2- air. 3- NH 4+ The process achieves the removal of SO2 from the tail gas. The cyanide tailings slurry after removal of cyanide (i.e., the cyanide tailings) is mechanically filtered to form a cyanide filter cake and filtrate. After being crushed by a crusher, the filter cake is fed into the flue gas drying cylinder together with the desulfurized gypsum to achieve dehydration of the desulfurized gypsum and the cyanide tailings. After the above-mentioned removal of cyanide, filtration and drying processes, the desulfurized gypsum and cyanide tailings achieve removal of cyanide, desalination and dehydration. The above-mentioned cyanide tailings and desulfurized gypsum have initially achieved the accuracy of raw material matching.

[0064] The cyanide tailings after decyanation, filtration, and crushing, and the desulfurized gypsum after filtration and crushing are sent to a dryer for drying to form a mixture, which is then mixed with secondary aluminum ash. The heat source of the dryer comes from part of the high-temperature flue gas generated by the calcining kiln for preparing clinker of special cementitious materials of sulfoaluminate.

[0065] Based on the composition of the raw materials in the dryer, corrective materials are added (because the moisture content and composition fluctuations of desulfurized gypsum and cyanide tailings filter cake after drying affect the final composition of the proportion, and the chloride salts contained in the secondary aluminate ash also affect the total composition of the matched materials, the final composition of the raw materials needs to be corrected. Corrective materials are added appropriately according to the content of the initial batching) (secondary aluminate ash, limestone (after drying), desulfurized gypsum (after drying), chloride salts) to match the raw materials, forming the raw meal of sulfoaluminate cementitious material and the chloride salt content required for the maximum value of precious metal chlorination gasification in the raw meal. Based on the mass fraction of the matched raw meal solids after drying, the composition is as follows: desulfurized gypsum: 53, secondary aluminate ash: 21, decyanate tailings: 18, corrective material (stone powder): 8.

[0066] The matched raw materials, after drying and grinding, are directly fed into a rotary kiln for calcination at 1260℃ for 60 minutes. To further stabilize the calcium sulfoaluminate, dicalcium silicate, and magnesium aluminum spinel mineral system and to ensure more thorough decomposition of some calcium sulfate, the calcination time can be extended. The generated high-temperature flue gas undergoes heat exchange with multiple washing processes, and the raw materials are dried using a surface-type waste heat recovery system, achieving a moisture content of less than 1% after drying.

[0067] After multiple washes (each wash using a saturated sodium bisulfite solution), the rotary kiln flue gas temperature is reduced to 150℃. After dust removal, it is prepared as SO2 tail gas with a concentration of 24%, and continues to react with cyanide in the decyanation reaction tank to produce HCO3-. 3- NH 4+ Cyanide tailings slurry, after being filtered, crushed, and dried, is mixed with desulfurized gypsum and secondary alumina ash to prepare sulfoaluminate cementitious material raw material. The solid-liquid mixture generated after multiple washing processes is fed into a filter press for solid-liquid separation; the solid is used to extract precious gold and silver, and the liquid is used to extract copper and zinc. The sulfoaluminate cementitious material produced in the rotary kiln is cooled by an indirect cooler to obtain sulfoaluminate cementitious material clinker, such as... Figure 2 As shown, the main phases of the material are 3CaO·3Al2O3·CaSO4, 2CaO·SiO2 and iron phase, with a small amount of MgAl2O4. The main mineral phase content is 82%, iron phase is 7%, magnesium aluminum spinel is 4%, and there are also some undecomposed calcium sulfate and other impurity mineral phases.

[0068] The concentrations of total cyanide compounds in the cyanide tailings before and after decyanation are shown in the table below.

[0069]

[0070]

[0071] The content of precious metals in cyanide tailings and sulfoaluminate clinker is shown in the table below.

[0072] composition Au Ag Cyanide tailings (wt%) 3.64g / t 42.73g / t Sulfoaluminate clinker (wt%) 0.09g / t 2.86g / t

[0073] Example 2

[0074] A method for the overall detoxification of cyanide tailings and the synergistic preparation of sulfoaluminate cementitious materials for the recovery of precious metals is as follows:

[0075] like Figure 1 As shown, the cyanide tailings (gold grade 3.64 g / t, gold particle size less than 10 μm) are first treated in a decyanation tank, where the cyanide inside is converted into HCO3- under the reduction of copper ion catalyst and SO2- air. 3- NH 4+ The process achieves the removal of SO2 from the tail gas. The cyanide tailings slurry after removal of cyanide (i.e., the cyanide tailings) is mechanically filtered to form a cyanide filter cake and filtrate. After being crushed by a crusher, the filter cake is fed into the flue gas drying cylinder together with the desulfurized gypsum to achieve dehydration of the desulfurized gypsum and the cyanide tailings. After the above-mentioned removal of cyanide, filtration and drying processes, the desulfurized gypsum and cyanide tailings achieve removal of cyanide, desalination and dehydration. The above-mentioned cyanide tailings and desulfurized gypsum have initially achieved the accuracy of raw material matching.

[0076] The cyanide tailings after decyanation, filtration, and crushing, and the desulfurized gypsum after filtration and crushing are sent to a dryer for drying to form a mixture, which is then mixed with secondary aluminum ash. The heat source of the dryer comes from part of the high-temperature flue gas generated by the calcining kiln for preparing clinker of special cementitious materials of sulfoaluminate.

[0077] Based on the composition of the raw materials in the dryer, corrective material is added (because the moisture content and composition fluctuations of desulfurized gypsum and cyanide tailings filter cake after drying affect the final composition of the proportion, and the chloride salts contained in the secondary aluminate ash also affect the total composition of the matched materials, the final composition of the raw materials needs to be corrected. Corrective material is added appropriately according to the content of the initial batching) (secondary aluminate ash, limestone (after drying), desulfurized gypsum (after drying), chloride salts) to match the raw materials, forming the sulfoaluminate cementitious material raw meal and the chloride salt content required for the maximum value of precious metal chlorination gasification in the raw meal. Based on the mass fraction of the matched raw meal solids after drying, the composition is as follows: desulfurized gypsum: 48, secondary aluminate ash: 24, decyanate tailings: 21, corrective material (stone powder): 7.

[0078] The matched raw materials, after drying and grinding, are directly fed into a rotary kiln for calcination at 1280℃ for 40 minutes. To further stabilize the calcium sulfoaluminate, dicalcium silicate, and magnesium aluminum spinel mineral system and to ensure more thorough decomposition of some calcium sulfate, the calcination time can be extended. The generated high-temperature flue gas undergoes heat exchange with multiple washing processes, and the raw materials are dried using a surface-type waste heat recovery system, achieving a moisture content of less than 1% after drying.

[0079] After multiple washes (each wash using a saturated sodium bisulfite solution), the rotary kiln flue gas temperature is reduced to 150℃. After dust removal, it is prepared as SO2 tail gas with a concentration of 21%, and continues to react with cyanide in the decyanation reaction tank to produce HCO3-. 3- NH 4+ After cyanide tailings slurry is filtered, crushed, and dried, it is mixed with desulfurized gypsum and secondary aluminum ash to prepare sulfoaluminate cementitious material raw material. The solid-liquid mixture generated after multiple washings is fed into a filter press to achieve solid-liquid separation. The solid is used to extract precious gold and silver, and the liquid is used to extract copper and zinc. The sulfoaluminate cementitious material produced in the rotary kiln is cooled by an indirect cooler to obtain sulfoaluminate cementitious material clinker. The main phases of the material are 3CaO·3Al2O3·CaSO4, 2CaO·SiO2, and iron phase, with a small amount of MgAl2O4. The main mineral phase content is 83%, iron phase is 6%, magnesium aluminum spinel is 4%, and there are also a small amount of undecomposed calcium sulfate and other impurity mineral phases.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash, characterized in that, Includes the following steps: Using sulfur dioxide tail gas, partial decyanation treatment of cyanide tailings was carried out through the Inco process to obtain decyanated tailings. The cyanide tailings are mixed with desulfurization gypsum, secondary aluminum ash, and correction material, and then calcined to obtain sulfoaluminate cementitious clinker and the sulfur dioxide tail gas.

2. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 1, characterized in that, The partial cyanide removal process involves passing sulfur dioxide tail gas into a cyanide tail slurry containing a copper ion catalyst for treatment.

3. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 2, characterized in that, The specific process is as follows: the cyanide tailings are sent into an aeration water-soluble tank. The water in the water-soluble tank is industrial water containing a soluble copper catalyst. The cyanide tailings, soluble copper catalyst and industrial water are thoroughly mixed to prepare a slurry to be reacted. In a neutral to weakly alkaline solution, under the action of the soluble copper catalyst, sulfur dioxide tail gas and air are introduced. The synergistic effect of sulfur dioxide and air is used to oxidize cyanide into cyanate ions with lower toxicity, which are further oxidized into bicarbonate and ammonia.

4. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 3, characterized in that, The sulfur dioxide tail gas is compressed into compressed gas and then fed into a cyanide tailings slurry containing a copper ion catalyst.

5. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 4, characterized in that, The treated slurry is filtered to obtain wet cyanide tailings. The wet cyanide tailings are then crushed and dried to obtain cyanide tailings.

6. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 1, characterized in that, The sulfur dioxide tail gas is obtained by washing and removing dust from the flue gas after calcination.

7. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 1, characterized in that, The weight ratio of decyanation tailings, desulfurization gypsum, secondary aluminum ash, and corrective material is 16~25:30~55:18~25:7~13; Alternatively, a corrective agent may be added to make the basicity coefficient of the mixed raw materials before calcination greater than 0.95 and the sulfur dioxide concentration in the flue gas exceed 20%.

8. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 7, characterized in that, The weight ratio of decyanation tailings, desulfurization gypsum, secondary aluminum ash, and corrective material is 18~21:48~53:21~24:7~8; Alternatively, add a corrective agent at a ratio of 7-8%.

9. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 1, characterized in that, Corrective material is added when cyanide removal tailings, desulfurization gypsum, and secondary aluminum ash are mixed. Alternatively, desulfurization gypsum and decyanation tailings wet residue can be dried together and then mixed with secondary aluminum ash; Alternatively, desulfurized gypsum, wet residue from decyanation tailings, and secondary aluminum ash can be homogenized, mixed, and dried.

10. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 1, characterized in that, The calcination temperature is 1200~1300℃; Alternatively, the calcination time is 40~70 minutes.

11. The method for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 10, characterized in that, The calcination temperature is 1250~1280℃; Alternatively, the calcination time is 40 minutes.

12. A system for the integrated detoxification of cyanide tailings and synergistic preparation of cementitious materials using secondary aluminum ash, characterized in that, To implement the method according to any one of claims 1 to 11, comprising: The Inco process decyanation reactor is used to partially decyanate sulfur dioxide tail gas by using the Inco process to treat cyanide tailings, producing decyanated tailings. The mixing and calcining device is used to mix the decyanation tailings from the Incorea decyanation reactor with desulfurization gypsum, secondary aluminum ash, and corrective material, and then calcine them to produce sulfoaluminate cementitious clinker and sulfur dioxide tail gas, and then transport the sulfur dioxide tail gas to the Incorea decyanation reactor.

13. The system for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings and secondary aluminum ash as described in claim 12, characterized in that, It includes a flue gas scrubbing device that removes precious metals from the calcined flue gas by chlorination to obtain sulfur dioxide tail gas, and then sends the sulfur dioxide tail gas to the Inco decyanation reaction unit.

14. The system for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings secondary aluminum ash as described in claim 12, characterized in that, It includes a drying device for drying the wet residue of desulfurized gypsum and decyanation tailings produced by the Inco process.

15. The system for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings secondary aluminum ash as described in claim 12, characterized in that, It includes a surface-type waste heat recovery unit, which is used to provide the waste heat of the calcination flue gas generated by the mixing and calcining device as heat to the drying device.

16. The system for the overall detoxification and synergistic preparation of cementitious materials from cyanide tailings secondary aluminum ash as described in claim 15, characterized in that, The surface-type waste heat recovery unit uses the heat from the high-temperature solid-liquid mixture generated by the washing device through the washing of calcination flue gas to dry and heat the raw material in the drying device, so that the total moisture content of the raw material is less than 2%.

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