Arsenic-calcium slag all-component resource utilization method

Abstract

The invention discloses an arsenic-calcium slag all-component resource utilization method, and belongs to the technical field of solid waste resource utilization. Uniformly mixing the arsenic-calcium slag with a calcium fluoride-calcium chloride composite additive, and carrying out reduction roasting to obtain roasted slag; flue gas generated by reduction roasting is subjected to multi-stage condensation, and lead-zinc compounds and elemental arsenic are recovered respectively; the roasting slag and an iron sulfide-sodium sulfide composite trapping agent are evenly mixed for high-temperature smelting, alloy melt is obtained, and hot-state smelting slag is discharged; reacting the hot-state smelting slag with nano silicon powder to generate modified smelting slag containing beta-C2S phase; and finely grinding the modified smelting slag, adding an alkali activator, and carrying out polymerization reaction to obtain the building material. According to the method, the arsenic-calcium slag solid waste serves as the raw material, high-added-value products such as elemental arsenic, alloys and building materials can be obtained, and all-component resource utilization of the arsenic-calcium slag solid waste is truly achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to an arsenic-calcium slag treatment method, in particular to a full-component resource utilization method of arsenic-calcium slag, and belongs to the technical field of solid waste resource utilization. BACKGROUND

[0002] Arsenic-calcium slag is a hazardous waste produced in the flue gas acid washing process of heavy metal smelting (copper, zinc, lead, etc.), containing high concentrations of arsenic (As), heavy metals (Cd, Pb, Cu, etc.), fluorine (F), chlorine (Cl) and residual sulfuric acid, and has strong toxicity and high environmental risk. There are three technical bottlenecks in the current treatment of arsenic-calcium slag: first, the calcium arsenate crystal structure is stable (Ca-As-O bond dissociation energy > 800 kJ / mol), and conventional reduction requires high temperature above 1250℃, resulting in high energy consumption (1.8 tons of standard coal per ton of slag) and arsenic volatilization loss; second, the associated copper, lead, indium and other metals in the slag have large differences in melting point, and are prone to segregation during smelting separation, with a recovery rate generally lower than 85%; third, the free CaO in the calcium slag expands when it comes into contact with water, resulting in poor stability of building materials, and the physically encapsulated arsenic is easily leached out (>2mg / L) under acid rain erosion, which is difficult to meet the 0.5mg / L limit value of GB 5085.3-2007.

[0003] Chinese patent (publication number: CN110144463A) discloses a method for treating arsenic-calcium slag for resource utilization, which dries and dehydrates the arsenic-calcium slag, reduces and roasts it, and then performs flotation and secondary roasting to obtain high-grade arsenic trioxide, and the tailings are used as a cement additive. This method essentially only recovers the arsenic resources in the arsenic-calcium slag, and the valuable metals in the tailings are not fully recovered. SUMMARY

[0004] In view of the technical defects of the prior art, the purpose of the present application is to provide a full-component resource utilization method of arsenic-calcium slag, which uses arsenic-calcium slag solid waste as raw material and can obtain high-value-added products such as elemental arsenic, alloys and building materials, truly realizing the full-component resource utilization of arsenic-calcium slag.

[0005] In order to achieve the above technical purpose, the present application provides a full-component resource utilization method of arsenic-calcium slag, which comprises the following steps:

[0006] 1) uniformly mixing arsenic-calcium slag with calcium fluoride-calcium chloride complex additives for reduction roasting to obtain roasted slag; the flue gas generated by the reduction roasting is subjected to multi-stage condensation to recover lead-zinc compounds and elemental arsenic, respectively;

[0007] 2) uniformly mixing the roasted slag with iron sulfide-sodium sulfide complex trapping agent for high-temperature smelting to obtain an alloy melt and discharge hot smelting slag;

[0008] 3) reacting the hot smelting slag with nano-silicon powder to generate modified smelting slag containing beta-C2S phase;

[0009] 4) grinding the modified smelting slag, adding alkali activator to carry out geopolymerization reaction to obtain building materials.

[0010] The method for full-component resource utilization of arsenic-calcium slag provided by the application first volatilizes and recovers elemental arsenic from the arsenic-calcium slag through a reduction roasting method, and the key in the reduction roasting process is the use of calcium fluoride-calcium chloride composite additive, which can destroy the phase structure of the arsenic-calcium slag on the one hand to promote the low-temperature conversion of calcium arsenate and the efficient volatilization of arsenic, and on the other hand can realize the chlorination volatilization of lead, zinc and other metals to realize the separation of lead, zinc and other metals, and the volatilized lead, zinc and other metals can be separated and recovered through a multi-stage condensation method. Secondly, copper, lead, indium and other metals are still left in the roasting slag, and the application realizes the recovery of copper, lead, indium and other metals through high-temperature smelting, and uses iron sulfide-sodium sulfide composite collector in the high-temperature smelting process, which can form a eutectic body (melting point 880℃) at high temperature, and has high solubility for copper, lead, indium and other metals, which is beneficial to improve the recovery rate of copper, lead, indium and other metals. Thirdly, the main component of the smelting slag after recovery of valuable metals is active calcium oxide, and the key of the application is to add silicon powder to the hot smelting slag just discharged to realize the high-temperature conversion of active calcium oxide to obtain beta-C2S phase with high activity, which is easy to obtain building materials through alkali activation. In summary, the application recovers useful metals in arsenic-calcium slag in steps, and the final slag phase is used as building materials, which truly realizes the full-component resource utilization of arsenic-calcium slag.

[0011] As a preferred scheme, the calcium fluoride-calcium chloride composite additive is composed of calcium fluoride and calcium chloride in a mass ratio of 1:1.5-2.5. By using the calcium fluoride-calcium chloride composite additive, the calcium arsenate crystal structure dissociation energy can be significantly reduced, and the calcium arsenate structure can be effectively destroyed at a relatively low temperature. The calcium fluoride and calcium chloride in the calcium fluoride-calcium chloride composite additive have a significant synergistic effect. On the one hand, the calcium fluoride and calcium chloride form a low-temperature eutectic system. CaCl2 (melting point 772°C) is melted into a liquid phase at 1050°C, and forms a CaF2-CaCl2 eutectic system (eutectic point 734°C) with CaF2, which wraps the calcium arsenate particles and increases the solid-liquid reaction contact area (SEM shows that the reaction interface is expanded by 5 times). On the other hand, the fluorine ions generated by the calcium fluoride can promote the destruction of the calcium arsenate structure. The fluorine apatite structure (Ca5(AsO4)3F) formed by the fluorine ions and the calcium arsenate has a thermal decomposition temperature reduced from 1250°C to 950°C (verified by TG-DSC). Since the F-As bond energy (515 kJ / mol) is lower than the O-As bond energy (623 kJ / mol), the calcium chloride used in combination can promote the volatilization of arsenic oxides generated by the decomposition of calcium arsenate. CaCl2 reacts with As2O5 to generate gaseous chloroarsenic compounds (such as AsCl3, boiling point 130.2°C). In addition, the ratio of calcium fluoride and calcium chloride needs to be controlled within an appropriate range to effectively promote the decomposition of calcium arsenate and the volatilization of arsenic oxides. If the proportion of calcium fluoride is low, the calcium arsenate structure is difficult to effectively destroy, and if the proportion of calcium chloride is low, the volatilization and recovery efficiency of arsenic is reduced.

[0012] As a preferred scheme, the addition amount of the calcium fluoride-calcium chloride composite additive is 25-35% of the mass of the calcium arsenate slag. The addition amount of the calcium fluoride-calcium chloride composite additive directly affects the decomposition of the calcium arsenate slag phase and the volatilization of arsenic. If the addition amount is too small, the decomposition of the calcium arsenate slag phase is incomplete, and the arsenic recovery rate is low. If the addition amount is too high, it causes waste and increases the cost.

[0013] As a preferred scheme, the reduction roasting conditions are as follows: the volume composition of the atmosphere is CO / (CO+CO2)=20-30%; the temperature is 1000-1100°C, and the time is 90-150 minutes. Under the preferred reduction roasting conditions, the arsenic reduction and volatilization efficiency can be improved, and the reduction and volatilization rate of arsenic is ≥99.5%.

[0014] As a preferred scheme, the multi-stage condensation includes three-stage condensation temperature intervals: the temperature of the first-stage condensation temperature interval is 650±10℃, the temperature of the second-stage condensation temperature interval is 320±5℃, and the temperature of the third-stage condensation temperature interval is 150±5℃; the flue gas sequentially passes through the three-stage condensation temperature intervals, the lead-zinc compounds in the flue gas are condensed and recovered in the first-stage condensation temperature interval, the elemental arsenic in the flue gas is condensed into liquid in the second-stage condensation temperature interval, and the elemental arsenic is condensed into arsenic ingot in the third-stage condensation temperature interval. The multi-stage condensation process of the present application efficiently removes lead, zinc and other impurities at a high temperature of 650±10℃, the removal rate is not less than 99.1%, the influence on the purity of elemental arsenic is avoided, the arsenic vapor is liquefied at a medium temperature of 320±5℃, the condensation efficiency of arsenic is not less than 99.5%, the liquid arsenic is further condensed into ingot at a low temperature of 150±5℃, and the purity of the obtained metallic arsenic is not less than 99.97%.

[0015] As a preferred scheme, the iron sulfide-sodium sulfide composite collector is composed of iron sulfide and sodium sulfide in a molar ratio of 1.5-2.5:1. The preferred iron sulfide-sodium sulfide composite collector has good solubility to copper, lead, indium and other metals, can target capture these metals, and the metal recovery rate is >95%. The iron sulfide-sodium sulfide composite collector forms a eutectic body (melting point 880℃) at high temperature, and the solubility rates of copper, lead and indium are 96.8%, 95.3% and 95.6%, respectively. In the iron sulfide-sodium sulfide composite collector of the present application, iron sulfide (FeS) is the main component, mainly as a sulfur source and a crystal nucleus, FeS is dissociated into S 2- after high-temperature melting, reacts with metals (Cu, Pb, In, etc.) to generate sulfides (Cu2S, PbS, In2S3), and can guarantee complete sulfuration of the metals. Meanwhile, the FeS melt (density 4.8 g / cm³) matches the density of other metal sulfides (Cu2S 5.6 g / cm³), can form a eutectic network structure (SEM shows that the dendrite spacing is <5 μm), and can physically capture micron-sized metal droplets. Sodium sulfide as a secondary component mainly reduces the melt viscosity, and after melting, Na + and S 2- are ionized, Na + is embedded in the silicate network, the slag viscosity is reduced, and the diffusion coefficient is improved. The activity (α 2- =10 s ) of S -8 dissociated from sodium sulfide is higher than that of FeS, and low-concentration metals (such as In, concentration only 85 g / t) are preferentially sulfurized, solving the problem that some metals are difficult to be sulfurized due to low concentration. As can be seen, the combination of iron sulfide and sodium sulfide plays a good synergistic role in capturing and sulfurizing metals.

[0016] As a preferred scheme, the adding amount of the iron sulfide-sodium sulfide composite collector is 15-18% of the mass of the calcined slag. If the relative adding amount of the iron sulfide-sodium sulfide composite collector of the present application is too small, it is difficult to improve the recovery rate of copper, lead, indium and other metals, and if the adding amount is too high, the increase of the metal recovery rate is not obvious.

[0017] As a preferred scheme, the high-temperature smelting includes a process flow of high-temperature zone smelting, slow cooling zone cooling and rapid cooling zone forming; the conditions of the high-temperature zone smelting are that the temperature is 1150-1250℃ and the time is 20-40 minutes; the conditions of the slow cooling zone cooling are that the cooling rate is 1-3℃ / min to 400℃; the conditions of the rapid cooling zone forming are that the cooling rate is >500℃ / s. The high-temperature smelting is cooperatively regulated by the three-temperature zones of the belt furnace, the molten pool residence time is optimized to 15 minutes and the slag-gold interface tension is 0.25 N / m in the high-temperature zone, the metal yield is increased to more than 96.8%, the cooling rate is controlled to 2℃ / min in the slow cooling zone (800℃ to 400℃) to make the indium segregation degree ≤4.2%, and the cooling rate is >500℃ / s in the rapid cooling zone to form a 3.0±0.1 mm thin strip, thereby ensuring the uniformity of the alloy composition.

[0018] As a preferred scheme, the adding amount of the nano silicon powder is 5-10wt% of the hot-state smelting slag. The temperature of the hot-state smelting slag discharged from the smelting furnace is generally >800℃, the nano silicon powder (particle size 50nm) is sprayed, the free CaO in the hot-state smelting slag is reduced from 5-8% to 0.75%, the high-activity β-C2S phase is generated, and the 28-day activity index of the slag body reaches 83.5% (strength 35.2MPa, GB / T 18046-2017).

[0019] As a preferred scheme, the modified smelting slag is finely ground to a specific surface area of more than 400m² / kg. By finely grinding the modified smelting slag to an appropriate specific surface area, the activation thereof can be improved.

[0020] As a preferred scheme, the alkali activator is composed of sodium silicate with a modulus of 1.0-1.4 and 4-8mol / L NaOH at a volume ratio of 2-4:1. The network structure of [AsO4]³ - is replaced by [SiO4] 4- , the arsenic is effectively fixed, and the leaching concentration of residual arsenic is as low as 0.08mg / L (HJ557-2010), which is much lower than the limit value of GB 5085.3-2007.

[0021] As a preferred scheme, the alkali activator is metered with the modified smelting slag at a solid-liquid ratio of 1 kg: 0.3-0.5 L. The geopolymerization reaction can occur in the modified smelting slag by alkali activation to effectively fix a small amount of residual metal (such as arsenic leaching <0.1 mg / L) in the smelting slag, and the geopolymer material meets the application requirements of building materials.

[0022] Compared with the prior art, the present application has the beneficial technical effects:

[0023] Compared with the traditional arsenic-calcium slag treatment process, the energy consumption per ton of slag is reduced from 1.8 tons of standard coal to 1.26 tons (a decrease of 30%), the purity of arsenic ingot is increased from 97.5% to 99.97%, the indium recovery rate is increased from 83.7% to 95.6%, the free CaO content of calcium slag is reduced by more than 84% (≤0.75%), the 28-day compressive strength of building material products is increased by 57% (up to 35.2 MPa), and after the solidified body is subjected to 180-day acid rain simulation (pH=3.2), the cumulative release amount of arsenic is only 0.09 mg / L (a decrease of 92.5%), and the stability is significantly better than the specification requirement of HJ 1091-2020.

[0024] The present application is directed to a treatment process for arsenic-calcium slag (HW24 hazardous waste) containing 10-35wt% of arsenic, which solves the industry pain points in the traditional process, such as high arsenic reduction temperature (≥1250℃), low multi-metal recovery rate (<85%), high free calcium oxide content (5-8%) in calcium slag building materials, and arsenic leaching risk (>2mg / L). Through the process combining calcium fluoride-calcium chloride complex additives alteration, gradient condensation, multi-metal targeted enrichment, and slag body mineral phase reconstruction technology, the synergistic treatment target of arsenic reduction rate ≥99.5%, valuable metal recovery rate >95%, calcium slag activity index ≥80%, and arsenic leaching concentration <0.1mg / L is achieved, which meets the arsenic leaching limit value (≤0.5mg / L) of GB 5085.3-2007 and the building material activity requirement of GB / T 18046-2017. DETAILED DESCRIPTION

[0025] The following specific examples are intended to further illustrate the content of the present application, but not to limit the protection scope of the claims.

[0026] Example 1

[0027] For example, 10 tons of arsenic-calcium slag (containing 28.5wt% of arsenic, 1.2wt% of copper, 3.5wt% of lead, and 85g / t of indium) are treated:

[0028] Step 1: Low-temperature reduction and high-purity arsenic recovery:

[0029] The arsenic-calcium slag was crushed to -100 mesh, and the composite additive was prepared by mixing calcium fluoride and calcium chloride at a mass ratio of 1:1.8. The addition amount of the composite additive was 30% of the mass of the arsenic-calcium slag. A mixed gas with a CO concentration of 25% (CO / (CO+CO2)=25%) was introduced into the reduction furnace, and the reaction was carried out at 1050°C for 120 minutes. XRD confirmed that the characteristic peaks of calcium arsenate disappeared, the arsenic content of the residue was reduced to 0.028wt% (ICP-MS), and the reduction rate was 99.72%. The generated arsenic-containing vapor was introduced into a three-stage condensation system: the first stage removed lead and zinc impurities at 650±10°C (condensate Pb content 92.4wt%, removal rate 99.1%); the second stage liquefied arsenic at 320±5°C (liquid arsenic collection rate 99.5%); and the third stage condensed arsenic into ingots under the protection of nitrogen flow 5L / min, obtaining arsenic ingots with purity 99.97% (GD-MS detected Fe<8ppm, Pb<12ppm).

[0030] Step 2: Multi-metal targeted enrichment and alloy regulation

[0031] After reduction, the slag was transferred to a belt furnace and a composite trapping agent of iron sulfide-sodium sulfide (molar ratio 2:1) was added at 17% of the mass of the slag. The reaction was carried out at a high temperature zone of 1200°C for 30 minutes. By optimizing the dam weir angle to 60° and the molten pool residence time to 15 minutes, the slag-gold interface tension was reduced to 0.25N / m, and the metal trapping rate was Cu 96.8%, Pb 95.3%, and In 95.6% (EPMA showed a sulfide inclusion rate of 97%). The melt entered the slow cooling zone (800°C to 400°C) at a cooling rate of 2°C / min. Electron probe confirmed that the indium segregation degree was 4.2%. Then, 3.0±0.1mm alloy strips were formed by water quenching thin strip technology (water pressure 0.5MPa, cooling rate >500°C / s) in the rapid cooling zone. XRF surface scanning showed that the copper content range was 0.6wt% (50-point detection).

[0032] Step 3: Calcium slag activation and arsenic stabilized building material preparation

[0033] The hot-state calcium slag (temperature >800°C) discharged from the belt furnace was sprayed into 50nm nano silicon powder (added at 8wt% of the hot-state calcium slag). In the slag pool turbulent zone, β-C2S phase was generated (XRD quantitative C2S content 68.3%), and free CaO was reduced to 0.75% (glycerol-ethanol method). The slag body had an activity index of 28.7MPa after 7 days. The modified slag was ground to a specific surface area of 450m² / kg. Alkali activator (sodium silicate with a modulus of 1.2 and 6mol / L NaOH at a volume ratio of 3:1) was added at a solid-liquid ratio of 1kg:0.35L. After stirring, it was poured into a mold and vibrated. It was demolded after 24 hours of 40°C curing, and then it was continuously cured at 25°C for 28 days. The geological polymer building material was obtained. FTIR detection showed an As-O-Si characteristic peak at 780cm -1 [AsO4]3- Embedded in the silicon-aluminum network; according to HJ 557-2010 acetic acid buffer method test, arsenic leaching concentration 0.08 mg / L (synchronous radiation XANES confirmed 95.3% arsenic was fixed in the form of As(V)), 28-day compressive strength of building materials 35.2 MPa (GB / T 17671-2021), meeting the requirements of GB 6566-2010 building materials.

[0034] Example 2

[0035] Take the treatment of 10 tons of arsenic-calcium residue (containing arsenic 30.2wt%, copper 1.3wt%, lead 3.0wt%, indium 79g / t) as an example:

[0036] Step 1: Low-temperature reduction and high-purity arsenic recovery:

[0037] The arsenic-calcium residue was crushed to -100 mesh, and the composite additive was formed by mixing calcium fluoride and calcium chloride at a mass ratio of 1:1.5, and the addition amount of the composite additive was 28% of the mass of the arsenic-calcium residue. A mixed gas with a CO concentration of 28% (CO / (CO+CO2)=28%) was introduced into the reduction furnace at 1080°C for 100 minutes, and the reduction rate was 99.83%. The generated arsenic-containing vapor was introduced into a three-stage condensation system: the first stage removed lead and zinc impurities at 650±10°C (condensate Pb content 93.3wt%, removal rate 99.4%); the second stage liquefied arsenic at 320±5°C (liquid arsenic collection rate 99.6%); and the third stage condensed arsenic into ingots under the protection of nitrogen flow 5L / min, obtaining arsenic ingots with purity 99.96%.

[0038] Step 2: Multi-metal targeted enrichment and alloy regulation:

[0039] The reduced slag was transferred to a belt furnace and added with 18% of the mass of the slag of iron sulfide-sodium sulfide composite capture agent (molar ratio 2.5:1), and melted at 1180°C for 40 minutes. By optimizing the dam weir angle to 60° and the molten pool residence time to 18 minutes, the slag-gold interface tension was reduced to 0.25N / m, and the metal capture rate was Cu 97.2%, Pb 96.1%, and In 95.5%. The melt entered the slow cooling zone (800°C to 400°C) at a rate of 2°C / min, and the electron probe confirmed that the indium segregation degree was 4.0%. Then, 3.0±0.1mm alloy strips were formed by water quenching thin strip technology (water pressure 0.5MPa, cooling rate >500°C / s) in the rapid cooling zone.

[0040] Step 3: Calcium slag activation and arsenic stabilization building material preparation

[0041] Hot calcium slag (temperature > 800℃) discharged from the belt furnace was sprayed into 50 nm nano-silicon powder (addition amount of 10wt% of hot calcium slag) by a spray gun, and β-C2S phase (XRD quantitative C2S content 70.1%) was generated in the slag pool turbulent flow zone, free CaO was reduced to 0.72% (glycerol-ethanol method), and the slag body 7-day activity index reached 29.4 MPa; the modified slag was ground to a specific surface area of 480 m² / kg, and an alkali activator (sodium silicate with a modulus of 1.2 and 6 mol / L NaOH were compounded at a volume ratio of 3:1) was added at a solid-liquid ratio of 1 kg:0.35 L, stirred and poured into a mold, vibrated, cured at 40℃ for 24 hours, demolded, and continued to be cured at 25℃ for 28 days. According to HJ 557-2010 acetic acid buffer method test, the arsenic leaching concentration was 0.06 mg / L, the 28-day compressive strength of building materials was 36.4 MPa (GB / T 17671-2021), which met the requirements of GB 6566-2010 building materials.

[0042] Example 3

[0043] Take the treatment of 10 tons of arsenic-calcium slag (containing arsenic 27.8wt%, copper 1.5wt%, lead 3.4wt%, indium 90g / t) as an example:

[0044] Step 1: Low-temperature reduction and high-purity arsenic recovery:

[0045] The arsenic-calcium slag was crushed to -100 mesh, mixed with calcium fluoride and calcium chloride to form a composite additive at a mass ratio of 1:2.2, and the addition amount of the composite additive was 32% of the mass of the arsenic-calcium slag. A mixed gas with a CO concentration of 26% (CO / (CO+CO2)=26%) was introduced into the reduction furnace at 1020℃ for 150 minutes, and the reduction rate was 99.20%. The generated arsenic-containing vapor was introduced into a three-stage condensation system: the first stage removed lead and zinc impurities at 650±10℃ (condensate Pb content 91.6wt%, removal rate 99.1%); the second stage liquefied arsenic at 320±5℃ (liquid arsenic collection rate 99.4%); and the third stage condensed arsenic into ingots under the protection of nitrogen flow 5L / min, obtaining arsenic ingots with purity 99.97%.

[0046] Step 2: Multi-metal targeted enrichment and alloy regulation:

[0047] The reduced slag is transferred to a belt furnace, and 15% of the mass of the slag is added with a ferrous sulfide-sodium sulfide composite trapping agent (molar ratio 1.6:1), and is melted and reacted at 1220°C in a high-temperature zone for 20 minutes. By optimizing the angle of the slag weir to 60° and the residence time in the molten pool to 18 minutes, the slag-metal interfacial tension is reduced to 0.25 N / m, and the metal trapping rate is 96.6% for Cu, 95.1% for Pb, and 95.0% for In. The melt enters a slow cooling zone (800°C to 400°C) and is cooled at a rate of 2°C / min. Electron probe analysis shows that the segregation degree of indium is 4.1%. Then, a water quenching thin strip technology (water pressure 0.5 MPa, cooling rate >500°C / s) is used to form an alloy strip with a thickness of 3.0±0.1 mm.

[0048] Step 3: Preparation of calcium slag activation and arsenic stabilized building materials

[0049] The hot-state calcium slag (temperature >800°C) discharged from the belt furnace is sprayed into 50 nm nano silicon powder (addition amount of 6wt% of the hot-state calcium slag) by a spray gun, and β-C2S phase is generated in the slag pool turbulent flow zone (XRD quantitative C2S content 68.2%), and the free CaO is reduced to 0.88% (glycerol-ethanol method), and the slag body has an activity index of 27.5 MPa after 7 days; the modified slag is ground to a specific surface area of 480 m² / kg, and an alkali activator (sodium silicate with a modulus of 1.2 and 6 mol / L NaOH are compounded in a volume ratio of 3:1) is added at a solid-liquid ratio of 1 kg:0.35 L, and after stirring, it is poured into a mold and vibrated, and cured at 40°C for 24 hours, demolded, and then cured at 25°C for 28 days, and according to the HJ 557-2010 acetic acid buffer method test, the arsenic leaching concentration is 0.07 mg / L, and the building material has a 28-day compressive strength of 34.1 MPa (GB / T 17671-2021), meeting the requirements of GB 6566-2010 for building materials.

[0050] Comparative Example 1

[0051] Compared with Example 1, the only difference is that calcium fluoride-calcium chloride composite additive is not used.

[0052]

[0053] Comparative Example 2

[0054] Compared with Example 1, the only difference is that a single calcium fluoride is used instead of a calcium fluoride-calcium chloride composite additive.

[0055]

Claims

1. A method for the complete resource utilization of arsenic-calcium slag, characterized in that: Includes the following steps: 1) Arsenic-calcium slag is mixed with calcium fluoride-calcium chloride composite additive and then reduced and roasted to obtain roasted slag; The flue gas produced by the reduction roasting is condensed in multiple stages to recover lead-zinc compounds and elemental arsenic. 2) The roasted slag is mixed with iron sulfide-sodium sulfide composite scavenger and smelted at high temperature to obtain alloy melt and hot smelting slag is discharged. 3) The hot smelting slag is reacted with nano-silicon powder to generate a modified smelting slag containing the β-C2S phase; 4) The modified smelting slag is finely ground and mixed with an alkali activator to carry out a polymerization reaction to obtain building materials.

2. The method for the complete resource utilization of arsenic-calcium slag according to claim 1, characterized in that: The calcium fluoride-calcium chloride composite additive is composed of calcium fluoride and calcium chloride in a mass ratio of 1:1.5~2.

5.

3. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 2, characterized in that: The amount of the calcium fluoride-calcium chloride composite additive added is 25-35% of the mass of the arsenic-calcium slag.

4. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 2, characterized in that: The conditions for the reduction roasting are as follows: the volume composition of the atmosphere is CO / (CO+CO2)=20~30%; the temperature is 1000~1100℃; and the time is 90~150 minutes.

5. The method for the complete resource utilization of arsenic-calcium slag according to claim 1, characterized in that: The multi-stage condensation includes three condensation temperature ranges: the temperature of the first-stage condensation temperature range is 650±10℃, the temperature of the second-stage condensation temperature range is 320±5℃, and the temperature of the third-stage condensation temperature range is 150±5℃. The flue gas passes through the three condensation temperature ranges in sequence. The lead and zinc compounds in the flue gas are condensed and recovered in the first-stage condensation temperature range, and the elemental arsenic in the flue gas is condensed into a liquid state in the second-stage condensation temperature range and condensed into arsenic ingots in the third-stage condensation temperature range.

6. The method for the complete resource utilization of arsenic-calcium slag according to claim 1, characterized in that: The iron sulfide-sodium sulfide composite trap is composed of iron sulfide and sodium sulfide in a molar ratio of 1.5~2.5:

1.

7. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 6, characterized in that: The amount of the iron sulfide-sodium sulfide composite scavenger added is 15-18% of the mass of the roasted slag.

8. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 6, characterized in that: The high-temperature melting process includes melting in a high-temperature zone, cooling in a slow cooling zone, and forming in a rapid cooling zone. The conditions for melting in the high-temperature zone are: temperature of 1150~1250℃ and time of 20~40 minutes. The conditions for cooling in the slow cooling zone are: cooling to 400℃ at a cooling rate of 1~3℃ / min. The conditions for forming in the rapid cooling zone are: cooling rate >500℃ / s.

9. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 6, characterized in that: The amount of nano-silicon powder added is 5-10 wt% of the hot smelting slag.

10. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 6, characterized in that: The modified smelting slag is finely ground to a specific surface area of ​​over 400 m² / kg; The alkaline activator is composed of sodium silicate with a modulus of 1.0 to 1.4 and 4 to 8 mol / L NaOH in a volume ratio of 2 to 4:

1. The alkali activator and the modified smelting slag are metered at a solid-liquid ratio of 1 kg: 0.3~0.5 L.

Images