Arsenic-calcium slag full-component resource utilization method

Abstract

The application discloses a kind of arsenic-calcium slag full-component resource utilization method, belong to solid waste resource utilization technical field.Arsenic-calcium slag is uniformly mixed with calcium fluoride-calcium chloride complex additive and is reduced roasting to obtain roasting slag;The flue gas generated by reduction roasting is recovered by multistage condensation respectively Lead-zinc compound and elemental arsenic;The roasting slag is uniformly mixed with iron sulfide-sodium sulfide complex trapping agent and is high-temperature smelting to obtain alloy melt and discharge hot smelting slag;Hot smelting slag is reacted with nano silicon powder to generate modified smelting slag containing β-C2S phase;The modified smelting slag is finely ground, and the alkali activator is added to carry out geopolymerization reaction to obtain building materials.The method uses arsenic-calcium slag solid waste as raw material, can obtain high value-added products such as elemental arsenic, alloy and building materials, and truly realizes the full-component resource utilization of arsenic-calcium slag solid.

Description

Technical Field

[0001] This invention relates to a method for treating arsenic-calcium slag, and more particularly to a method for the resource utilization of all components of arsenic-calcium slag, belonging to the field of solid waste resource utilization technology. Background Technology

[0002] Arsenic-calcium slag is a hazardous waste generated during the acid washing process of flue gas in heavy metal metallurgy (copper, zinc, lead, etc.). It contains high concentrations of arsenic (As), heavy metals (Cd, Pb, Cu, etc.), fluorine (F), chlorine (Cl), and residual sulfuric acid, posing a high toxicity and environmental risk. Current treatment of arsenic-calcium slag faces three major technical bottlenecks: First, calcium arsenate has a stable crystal structure (Ca-As-O bond dissociation energy >800kJ / mol), requiring conventional reduction at temperatures above 1250℃, resulting in excessively high energy consumption (1.8 tons of standard coal per ton of slag) and arsenic volatilization loss. Second, the associated metals such as copper, lead, and indium in the slag have large differences in melting points, easily leading to segregation during melting and separation, resulting in recovery rates generally below 85%. Third, free CaO in the calcium slag expands upon contact with water, leading to poor stability in building materials, and physically encapsulated arsenic is easily leached out under acid rain (>2mg / L), making it difficult to meet the 0.5mg / L limit of GB 5085.3-2007.

[0003] Chinese patent (publication number: CN110144463A) discloses a method for the resource utilization of arsenic-calcium slag. The method involves drying and dehydrating the arsenic-calcium slag, reducing and roasting it, flotation, and secondary roasting it to obtain high-grade arsenic trioxide. The tailings are used as cement additives. In essence, this method only recovers the arsenic resources in the arsenic-calcium slag, and the tailings are directly used as cement additives. However, the valuable metals in the tailings are not fully recovered. Summary of the Invention

[0004] In view of the technical defects of the existing technology, the purpose of this invention is to provide a method for the full-component resource utilization of arsenic-calcium slag. This method uses arsenic-calcium slag solid waste as raw material and can obtain high-value-added products such as elemental arsenic, alloys and building materials, thus truly realizing the full-component resource utilization of arsenic-calcium slag solid waste.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a method for the resource utilization of all components of arsenic-calcium slag, which includes the following steps:

[0006] 1) Arsenic-calcium slag is mixed with calcium fluoride-calcium chloride composite additive and then subjected to 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) 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.

[0008] 3) The hot smelting slag is reacted with nano-silicon powder to generate a modified smelting slag containing the β-C2S phase;

[0009] 4) The modified smelting slag is finely ground and mixed with an alkali activator to carry out a polymerization reaction to obtain building materials.

[0010] The method for the complete resource utilization of arsenic-calcium slag provided by this invention firstly involves the volatilization and recovery of elemental arsenic from the arsenic-calcium slag through a reduction roasting method. The key to this reduction roasting process lies in the use of a calcium fluoride-calcium chloride composite additive. On one hand, this additive disrupts the phase structure of the arsenic-calcium slag, promoting the low-temperature conversion of calcium arsenate and the efficient volatilization of arsenic. On the other hand, it enables the volatilization of metals such as lead and zinc through chlorination, achieving the separation of these metals. The volatilized lead and zinc metals can then be separated and recovered from elemental arsenic through a multi-stage condensation method. Secondly, the roasted slag still contains residual metals such as copper, lead, and indium. This invention utilizes a high-temperature smelting method to recover these metals. During the high-temperature smelting process, a composite collector of iron sulfide and sodium sulfide is used. This composite collector can form a eutectic at high temperatures (melting point 880℃), exhibiting high solubility for metals such as copper, lead, and indium, thus improving the recovery rate of these metals. Furthermore, the main component of the smelting slag after recovering valuable metals is active calcium oxide. The key to this invention is the addition of silicon powder to the freshly discharged hot smelting slag to achieve high-temperature conversion of the active calcium oxide, thereby obtaining a highly active β-C2S phase, which is easily obtained as building material through alkaline activation. In summary, this invention truly achieves the full-component resource utilization of arsenic-calcium slag by recovering valuable metals from it in stages, with the final slag phase used as a building material.

[0011] As a preferred embodiment, 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 dissociation energy of the calcium arsenate crystal structure can be significantly reduced, and the calcium arsenate structure can be effectively destroyed at relatively low temperatures. In the calcium fluoride-calcium chloride composite additive, calcium fluoride and calcium chloride play a significant synergistic role. On the one hand, calcium fluoride and calcium chloride form a low-temperature eutectic system. CaCl2 (melting point 772℃) melts into a liquid phase at 1050℃ and forms a CaF2-CaCl2 eutectic with CaF2 (eutectic point 734℃), which encapsulates calcium arsenate particles and increases the solid-liquid reaction contact area (SEM shows that the reaction interface expands 5 times). On the other hand, the fluoride ions generated by calcium fluoride can promote the destruction of the calcium arsenate structure. The thermal decomposition temperature of the fluorapatite structure (Ca5(AsO4)3F) formed by fluoride ions and calcium arsenate drops from 1250℃ to 950℃ (TG-DSC verification). This is because the F-As bond energy (515kJ / mol) is lower than the O-As bond energy (623kJ / mol). The calcium chloride used in combination can promote the volatilization of arsenic oxides produced by the decomposition of calcium arsenate. CaCl2 reacts with As2O5 to generate gaseous chlorinated arsenic compounds (such as AsCl3, boiling point 130.2℃). Furthermore, the ratio of calcium fluoride to 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 structure of calcium arsenate will be difficult to break down effectively, while a low proportion of calcium chloride will reduce the efficiency of arsenic volatilization and recovery.

[0012] As a preferred embodiment, the amount of calcium fluoride-calcium chloride composite additive added is 25-35% of the mass of the arsenic-calcium slag. The amount of calcium fluoride-calcium chloride composite additive added directly affects the decomposition of the arsenic-calcium slag phase and the volatilization of arsenic. If the amount added is too small, the decomposition of the arsenic-calcium slag phase will be incomplete and the arsenic recovery rate will be low. If the amount added is too large, it will result in waste and increased costs.

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

[0014] As a preferred embodiment, the multi-stage condensation includes three condensation temperature ranges: the first-stage condensation temperature range is 650±10℃, the second-stage condensation temperature range is 320±5℃, and the third-stage condensation temperature range is 150±5℃. The flue gas sequentially passes through these three condensation temperature ranges. Lead and zinc compounds in the flue gas are condensed and recovered in the first-stage condensation temperature range, while elemental arsenic in the flue gas is condensed into liquid in the second-stage condensation temperature range and then condensed into arsenic ingots in the third-stage condensation temperature range. This multi-stage condensation process efficiently removes impurities such as lead and zinc at a high temperature of 650±10℃, with a removal rate of not less than 99.1%, avoiding any impact on the purity of elemental arsenic. Arsenic vapor liquefaction is achieved in the medium-temperature range of 320±5℃, with an arsenic condensation efficiency of not less than 99.5%. The liquid arsenic is further condensed into ingots in the low-temperature range of 150±5℃ to obtain metallic arsenic with a purity of not less than 99.97%.

[0015] As a preferred embodiment, 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 exhibits good solubility for metals such as copper, lead, and indium, enabling targeted collection of these metals with a metal recovery rate >95%. The iron sulfide-sodium sulfide composite collector forms a eutectic at high temperatures (melting point 880℃), achieving solubility rates of 96.8%, 95.3%, and 95.6% for copper, lead, and indium, respectively. In this invention, iron sulfide (FeS) is the main component of the iron sulfide-sodium sulfide composite collector, primarily serving as a sulfur source and crystal nucleus. After melting at high temperatures, FeS dissociates into sulfur. 2- FeS reacts with metals (Cu, Pb, In, etc.) to form sulfides (Cu₂S, PbS, In₂S₃), ensuring complete metal sulfidation. Simultaneously, the FeS melt (density 4.8 g / cm³) matches the density of other metal sulfides (Cu₂S 5.6 g / cm³), enabling the formation of a eutectic network structure (SEM shows dendrite spacing <5 μm), which can physically trap micron-sized metal droplets. Sodium sulfide, as a minor component, primarily reduces melt viscosity; upon melting, sodium sulfide ionizes into Na₂S. + and S 2- Na + Embedding in a silicate network reduces slag viscosity and increases the diffusion coefficient, while the sulfur released from sodium sulfide dissociates... 2- Activity (α) s =10 -8 The iron sulfide concentration is higher than that of FeS, and it preferentially sulfides low-concentration metals (such as In, with a concentration of only 85 g / t), solving the problem that some metals are difficult to sulfide due to their low concentration. Therefore, the combination of iron sulfide and sodium sulfide exhibits a good synergistic effect in capturing and sulfiding metals.

[0016] As a preferred embodiment, the amount of the iron sulfide-sodium sulfide composite collector added is 15-18% of the mass of the roasted slag. If the relative amount of the iron sulfide-sodium sulfide composite collector added in this invention is too small, it will be difficult to improve the recovery rate of metals such as copper, lead, and indium; if the amount added is too large, the increase in metal recovery rate is not significant.

[0017] As a preferred embodiment, the high-temperature melting process includes high-temperature melting, slow cooling, and rapid cooling forming. The conditions for high-temperature melting are: temperature 1150~1250℃, time 20~40 minutes; the conditions for slow cooling are: cooling to 400℃ at a cooling rate of 1~3℃ / min; and the conditions for rapid cooling forming are: cooling rate >500℃ / s. High-temperature melting utilizes the coordinated control of the three temperature zones in a belt furnace. In the high-temperature zone, the residence time in the molten pool is optimized to 15 minutes and the slag-gold interfacial tension is reduced to 0.25 N / m, increasing the metal yield to over 96.8%. In the slow cooling zone (800℃ to 400℃), the cooling rate is controlled at 2℃ / min to ensure indium segregation ≤4.2%. Finally, in the rapid cooling zone, a 3.0±0.1 mm thin strip is formed at a cooling rate >500℃ / s, ensuring the uniformity of the alloy composition.

[0018] As a preferred embodiment, the amount of nano-silicon powder added is 5-10 wt% of the hot smelting slag. The temperature of the hot smelting slag just discharged from the smelting furnace is generally >800℃. By spraying nano-silicon powder (particle size 50nm), the free CaO in the hot smelting slag is reduced from 5-8% to 0.75%, generating a highly active β-C2S phase. The slag activity index reaches 83.5% after 28 days (strength 35.2MPa, GB / T 18046-2017).

[0019] As a preferred embodiment, the modified smelting slag is finely ground to a specific surface area of ​​400 m² / kg or higher. Finely grinding the modified smelting slag to an appropriate specific surface area is beneficial for improving its activation activity.

[0020] As a preferred embodiment, the alkali 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. [AsO4]³ is constructed using a composite solution of sodium silicate with a modulus of approximately 1.2 and approximately 6 mol / L sodium hydroxide. - Replacement of [SiO4] 4- The network structure enables effective arsenic fixation, with residual arsenic leaching concentration as low as 0.08 mg / L (HJ557-2010), far below the limit of GB 5085.3-2007.

[0021] As a preferred embodiment, the alkali activator and the modified smelting slag are metered at a solid-liquid ratio of 1 kg: 0.3~0.5 L. The alkali-activated modified smelting slag can undergo a polymerization reaction to effectively fix small amounts of residual metals in the smelting slag (e.g., arsenic leaching <0.1 mg / L), while the polymerized material meets the application requirements of building materials.

[0022] Compared with the prior art, the beneficial technical effects of this invention are as follows:

[0023] Compared with traditional arsenic-calcium slag treatment processes, the energy consumption per ton of slag in this invention is reduced from 1.8 tons of standard coal to 1.26 tons (a reduction of 30%), the purity of arsenic ingots 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 materials is increased by 57% (reaching 35.2MPa), and the cumulative arsenic release of the solidified body after 180 days of acid rain simulation (pH=3.2) is only 0.09mg / L (a reduction of 92.5%), with stability significantly better than the requirements of HJ 1091-2020 standard.

[0024] This invention addresses the treatment process for arsenic-calcium slag (HW24 type hazardous waste) containing 10-35 wt% arsenic, resolving industry pain points in traditional processes such as high arsenic reduction temperature (≥1250℃), low multi-metal recovery rate (<85%), high free calcium oxide content (5-8%) during calcium slag materialization, and arsenic leaching risk (>2 mg / L). Through a combination of processes including calcium fluoride-calcium chloride composite additive alteration, gradient condensation, multi-metal targeted enrichment, and slag mineral phase reconstruction, the invention achieves a synergistic treatment target of arsenic reduction rate ≥99.5%, valuable metal recovery rate >95%, calcium slag activity index ≥80%, and arsenic leaching concentration <0.1 mg / L, meeting the arsenic leaching limit (≤0.5 mg / L) of GB 5085.3-2007 and the building material activity requirements of GB / T 18046-2017. Detailed Implementation

[0025] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims.

[0026] Example 1

[0027] Taking the treatment of 10 tons of arsenic-calcium slag (containing 28.5 wt% arsenic, 1.2 wt% copper, 3.5 wt% lead, and 85 g / t indium) as an example:

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

[0029] Arsenic-calcium slag was crushed to -100 mesh and mixed with calcium fluoride and calcium chloride at a mass ratio of 1:1.8 to form a composite additive. The amount of the composite additive added 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 reacted at 1050℃ for 120 minutes. XRD confirmed that the characteristic peak of calcium arsenate disappeared and the arsenic content of the residue was reduced to 0.028wt% (ICP-MS), with a reduction rate of 99.72%. The arsenic-containing vapor generated was introduced into a three-stage condensation system: the first stage at 650±10℃ removed lead and zinc impurities (condensate Pb content 92.4wt%, removal rate 99.1%), the second stage at 320±5℃ liquefied arsenic (liquid arsenic collection rate 99.5%), and the third stage at 150±5℃ condensed arsenic into ingots under nitrogen flow rate of 5L / min protection, obtaining arsenic ingots with a purity of 99.97% (GD-MS detection Fe<8ppm, Pb<12ppm).

[0030] Step 2: Targeted enrichment and alloy regulation of multimetals:

[0031] After reduction, the slag was transferred to a belt furnace, and 17% of the slag mass of an iron sulfide-sodium sulfide composite collector (molar ratio 2:1) was added. The furnace was then melted and reacted at a high temperature of 1200℃ for 30 minutes. By optimizing the slag weir angle to 60° and the molten pool residence time to 15 minutes, the slag-gold interfacial tension was reduced to 0.25 N / m, and the metal collection rates were Cu 96.8%, Pb 95.3%, and In 95.6% (EPMA showed a sulfide encapsulation rate of 97%). The melt was then cooled in a slow cooling zone (800℃ to 400℃) at a rate of 2℃ / min. Electron probe microanalysis confirmed an indium segregation of 4.2%. Subsequently, a 3.0±0.1 mm alloy strip was formed in the rapid cooling zone using water quenching thin strip technology (water pressure 0.5 MPa, cooling rate >500℃ / s). XRF surface scanning showed a copper content range of 0.6 wt% (50-point detection).

[0032] Step 3: Preparation of building materials by activation and arsenic stabilization of calcium slag

[0033] Hot calcium slag (temperature >800℃) discharged from a belt furnace was sprayed with 50nm nano-silica powder (8wt% of the hot calcium slag) through a spray gun. In the turbulent zone of the slag pool, a β-C2S phase was generated (XRD quantitative C2S content 68.3%), and the free CaO decreased to 0.75% (glycerol-ethanol method). The slag activity index reached 28.7MPa after 7 days. The modified slag powder was ground to a specific surface area of ​​450m² / kg, and an alkali activator (sodium silicate with a modulus of 1.2 and 6mol / L NaOH mixed at a volume ratio of 3:1) was added at a solid-liquid ratio of 1kg:0.35L. After stirring, the mixture was poured into a mold and compacted. It was cured at 40℃ for 24 hours, demolded, and then wet-cured at 25℃ for 28 days to obtain geopolymer building materials. FTIR analysis showed a 780cm... -1 The presence of characteristic As-O-Si peaks confirms the presence of [AsO4].3- Embedded silicon-aluminum network; tested according to HJ 557-2010 acetic acid buffer method, arsenic leaching concentration is 0.08 mg / L (synchrotron radiation XANES confirmed that 95.3% of arsenic is fixed in the form of As(V)), building material 28-day compressive strength is 35.2 MPa (GB / T 17671-2021), meeting the requirements of GB 6566-2010 building materials.

[0034] Example 2

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

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

[0037] Arsenic-calcium slag was crushed to -100 mesh and mixed with calcium fluoride and calcium chloride at a mass ratio of 1:1.5 to form a composite additive. The amount of the composite additive added was 28% of the mass of the arsenic-calcium slag. A mixed gas with a CO concentration of 28% (CO / (CO+CO2)=28%) was introduced into the reduction furnace and reacted at 1080℃ for 100 minutes, with a reduction rate of 99.83%. The arsenic-containing vapor generated was introduced into a three-stage condensation system: the first stage at 650±10℃ removed lead and zinc impurities (condensate Pb content 93.3wt%, removal rate 99.4%), the second stage at 320±5℃ liquefied arsenic (liquid arsenic collection rate 99.6%), and the third stage at 150±5℃ condensed arsenic into ingots under nitrogen flow rate of 5L / min protection, obtaining arsenic ingots with a purity of 99.96%.

[0038] Step 2: Targeted enrichment and alloy regulation of multimetals:

[0039] After reduction, the slag was transferred to a belt furnace, and 18% of the slag mass of the iron sulfide-sodium sulfide composite collector (molar ratio 2.5:1) was added. The furnace was melted and reacted in a high-temperature zone of 1180℃ for 40 minutes. By optimizing the slag weir angle to 60° and the residence time in the molten pool to 18 minutes, the slag-gold interfacial tension was reduced to 0.25 N / m, and the metal collection rates were Cu 97.2%, Pb 96.1%, and In 95.5%. The melt was then cooled in a slow cooling zone (800℃ to 400℃) at a rate of 2℃ / min. Electron probe microanalysis confirmed an indium segregation of 4.0%. Subsequently, a 3.0±0.1 mm alloy strip was formed in the rapid cooling zone using water quenching thin strip technology (water pressure 0.5 MPa, cooling rate >500℃ / s).

[0040] Step 3: Preparation of building materials by activation and arsenic stabilization of calcium slag

[0041] Hot calcium slag (temperature >800℃) discharged from a belt furnace was sprayed with 50nm nano-silica powder (10wt% of the hot calcium slag) through a spray gun. In the turbulent zone of the slag pool, a β-C2S phase was generated (XRD quantitative C2S content 70.1%), and the free CaO decreased to 0.72% (glycerol-ethanol method). The slag's activity index reached 29.4MPa after 7 days. The modified slag powder was ground to a specific surface area of ​​480m² / kg, and an alkali activator (sodium silicate with a modulus of 1.2 and 6mol / L NaOH mixed at a volume ratio of 3:1) was added at a solid-liquid ratio of 1kg:0.35L. After stirring, the mixture was poured into a mold and compacted. It was then demolded after curing at 40℃ for 24 hours and continued to be wet-cured at 25℃ for 28 days. According to the acetic acid buffer method of HJ 557-2010, the arsenic leaching concentration was 0.06mg / L, and the 28-day compressive strength of the building material was 36.4MPa (GB / T). (17671-2021), meets the requirements of GB 6566-2010 building materials.

[0042] Example 3

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

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

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

[0046] Step 2: Targeted enrichment and alloy regulation of multimetals:

[0047] After reduction, the slag was transferred to a belt furnace, and 15% of the slag mass of iron sulfide-sodium sulfide composite collector (molar ratio 1.6:1) was added. The furnace was melted and reacted in a high-temperature zone of 1220℃ for 20 minutes. By optimizing the slag weir angle to 60° and the residence time in the molten pool to 18 minutes, the slag-gold interfacial tension was reduced to 0.25 N / m, and the metal collection rates were Cu 96.6%, Pb 95.1%, and In 95.0%. The melt was then cooled in a slow cooling zone (800℃ to 400℃) at a rate of 2℃ / min. Electron probe microanalysis confirmed an indium segregation of 4.1%. Subsequently, a 3.0±0.1 mm alloy strip was formed in the rapid cooling zone using water quenching thin strip technology (water pressure 0.5 MPa, cooling rate >500℃ / s).

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

[0049] Hot calcium slag (temperature >800℃) discharged from a belt furnace was sprayed with 50nm nano-silica powder (6wt% of the hot calcium slag) through a spray gun. In the turbulent zone of the slag pool, a β-C2S phase was generated (XRD quantitative C2S content 68.2%), and the free CaO decreased to 0.88% (glycerol-ethanol method). The slag's activity index reached 27.5MPa after 7 days. The modified slag powder was ground to a specific surface area of ​​480m² / kg, and an alkali activator (sodium silicate with a modulus of 1.2 and 6mol / L NaOH mixed at a volume ratio of 3:1) was added at a solid-liquid ratio of 1kg:0.35L. After stirring, the mixture was poured into a mold and compacted. It was then demolded after curing at 40℃ for 24 hours and continued to be wet-cured at 25℃ for 28 days. According to the acetic acid buffer method of HJ 557-2010, the arsenic leaching concentration was 0.07mg / L, and the 28-day compressive strength of the building material was 34.1MPa (GB / T). (17671-2021), meets the requirements of GB 6566-2010 building materials.

[0050] Comparative Example 1

[0051] The only difference compared to Example 1 is that the calcium fluoride-calcium chloride composite additive was not used.

[0052]

[0053] Comparative Example 2

[0054] The only difference compared to Example 1 is that single calcium fluoride is used instead of the 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 generated by the reduction roasting is condensed in multiple stages to recover lead-zinc compounds and elemental arsenic. The conditions for the reduction roasting are: the volume composition of the atmosphere is CO / (CO+CO2)=20~30%; the temperature is 1000~1100℃; and the time is 90~150 minutes. 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. 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.

5. 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.

6. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 5, characterized in that: The amount of the iron sulfide-sodium sulfide composite scavenger added is 15-18% of the mass of the roasted slag.

7. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 5, 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.

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

9. A method for the complete resource utilization of arsenic-calcium slag according to claim 1 or 5, 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.

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