A method for resourceful treatment of sodium chloride-containing waste and polyvinyl chloride waste

Abstract

The application provides a resourceful treatment method of sodium chloride-containing waste and polyvinyl chloride waste, and belongs to the technical field of waste treatment. The resourceful treatment method comprises the following steps: mixing sodium chloride-containing waste, polyvinyl chloride waste, a promoter and a solid halogen agent, and performing calcination treatment to obtain calcined material; mixing the calcined material with water, and performing solid-liquid separation to obtain liquid material and solid material; the solid material is recovered promoter; and the liquid material is crystallized to obtain recovered sodium chloride. The resourceful treatment method can remove organic pollutants in the sodium chloride-containing waste, effectively fix the chlorine element in the polyvinyl chloride waste, prevent the chlorine element from escaping, and reduce the harm to the environment.

Description

A method for resource recovery of waste containing sodium chloride and polyvinyl chloride. Technical Field

[0001] This invention belongs to the field of waste treatment technology, specifically relating to a resource-based treatment method for waste containing sodium chloride and polyvinyl chloride. Background Technology

[0002] Waste salt refers to waste residues, dust, and other crystalline products generated during industrial production processes. It typically contains raw materials, products, or byproducts from the production process, and these waste salts generally consist of various complex organic compounds and are toxic. Waste sodium chloride constitutes a large proportion of waste salt, and currently, the main method used in this field is thermal treatment, such as incineration. However, due to the inherent physical properties of waste sodium chloride, it continuously vaporizes during thermal treatment, resulting in the release of chlorine. Moreover, the commonly used thermal treatment temperatures are generally 400–550°C, at which temperature conditions the residual organic pollutants in waste sodium chloride are difficult to remove.

[0003] Polyvinyl chloride (PVC) is one of the five most widely used plastics, primarily applied in building materials, packaging materials, electronic equipment, furniture, and decorative materials. However, after a period of use, the properties of PVC change, rendering the products unusable and thus confiscated as waste. Currently, the main method for treating waste PVC products is incineration. However, under the high temperatures (600–700°C) of incineration, a large amount of chloride (Cl)-containing substances in the waste PVC products react, generating hydrogen chloride gas, dioxins, and other toxic chloride-containing substances. Moreover, dioxins are highly carcinogenic with a half-life of over five years, posing a significant health risk. Therefore, how to fix chloride elements while treating waste PVC products to reduce environmental harm remains a major challenge. Summary of the Invention

[0004] The purpose of this invention is to provide a resource-based treatment method for sodium chloride-containing waste and polyvinyl chloride (PVC) waste. Using this method, the organic pollutants in the sodium chloride-containing waste can be removed, and the release of chlorine from the PVC waste can be effectively contained, thus reducing environmental harm.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for the resource recovery of waste containing sodium chloride and polyvinyl chloride, comprising the following steps:

[0007] Sodium chloride waste, polyvinyl chloride waste, accelerator and solid halogen agent are mixed and calcined to obtain calcined material; the accelerator is iron waste; the solid halogen agent is at least one of carbonate, bicarbonate, basic oxide and basic hydroxide; the calcination temperature is 400-550℃ and the holding time is 40-80min.

[0008] The calcined material is mixed with water and subjected to solid-liquid separation to obtain a liquid material and a solid material; the solid material is a recovery accelerator.

[0009] The liquid material is crystallized to obtain recycled sodium chloride.

[0010] Preferably, the particle size of the sodium chloride waste, polyvinyl chloride waste, and accelerator is independently 80-200 mesh.

[0011] Preferably, the mass fraction of sodium chloride in the sodium chloride-containing waste is ≥85%.

[0012] Preferably, the chlorine content in the polyvinyl chloride waste is 50-70% by mass.

[0013] Preferably, the polyvinyl chloride waste includes at least one of waste PVC water pipes and automotive PVC plastics.

[0014] Preferably, the accelerator includes at least one of hematite slag, chlorinated dust collector slag, iron slag, and metallurgical boiler residue.

[0015] Preferably, the accelerator contains 1-30% iron by mass.

[0016] Preferably, the carbonate is sodium carbonate and / or calcium carbonate; the bicarbonate is sodium bicarbonate; the alkaline oxide is sodium oxide and / or calcium oxide; and the alkaline hydroxide is sodium hydroxide and / or potassium hydroxide.

[0017] Preferably, the mass ratio of the sodium chloride waste, polyvinyl chloride waste, and accelerator is 40-160:10-40:2-7; and the molar ratio of the polyvinyl chloride waste and the solid halogen agent is 1:0.5-1.5.

[0018] Preferably, the calcination treatment is carried out in an air atmosphere, and the air flow rate is 80-150 mL / min.

[0019] This invention provides a method for the resource recovery treatment of sodium chloride-containing waste and polyvinyl chloride (PVC) waste, comprising the following steps: mixing sodium chloride-containing waste, PVC waste, an accelerator, and a solidifying agent, and calcining the mixture to obtain calcined material; wherein the accelerator is iron waste; and the solidifying agent is at least one selected from carbonates, bicarbonates, basic oxides, and basic hydroxides; the calcination temperature is 400–550°C, and the holding time is 40–80 min; mixing the calcined material with water and performing solid-liquid separation to obtain liquid material and solid material; wherein the solid material is a recovery accelerator; and crystallizing the liquid material to obtain recovered sodium chloride. This invention, in the presence of an accelerator, involves mixing sodium chloride-containing waste and polyvinyl chloride (PVC) waste for calcination. This not only effectively lowers the decomposition temperature of organic pollutants in the sodium chloride-containing waste and accelerates their decomposition, but also provides heat for the decomposition of organic pollutants in the waste sodium chloride, reducing the overall energy consumption of the system. Simultaneously, the halogen-fixing agent effectively fixes the chlorine element in the PVC waste, converting it into sodium chloride or other easily removed and separated inorganic substances, thus reducing environmental harm.

[0020] This invention uses iron-containing waste as a promoter, effectively lowering the decomposition temperature of organic pollutants in sodium chloride-containing waste. Under the presence of a halogen-fixing agent, the chlorine in polyvinyl chloride waste is fixed into inorganic sodium chloride, achieving resource recovery. This also avoids the generation of secondary pollutants such as hydrogen chloride and dioxins under high-temperature conditions. Furthermore, the promoter can be recovered and reused after resource recovery. Moreover, the resource recovery method provided by this invention has the advantages of being easy to implement, simple in process, and technically reliable. It not only achieves chlorine fixation and improves the salt regeneration rate but also reduces environmental pollution without increasing the discharge of waste gas, wastewater, and solid waste, resulting in high economic benefits. This invention provides a novel approach for the co-resource recovery of chemical waste salts.

[0021] Furthermore, when treating sodium chloride-containing waste according to the resource recovery method provided by this invention, the removal rate of organic pollutants in the sodium chloride-containing waste exceeds 99%, and the regeneration rate of the sodium chloride-containing waste reaches over 98%. Examples show that the resource recovery method provided by this invention can reduce the TOC content in recovered sodium chloride to 14.8–24.9 ppm, lower than the industrial treatment requirements; moreover, the Cl fixation rate in polyvinyl chloride waste exceeds 98%, and its treatment temperature is significantly lower than that of existing technologies (600–700°C); additionally, iron waste can be reused as an accelerator. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0024] This invention provides a method for the resource recovery of waste containing sodium chloride and polyvinyl chloride, comprising the following steps:

[0025] Sodium chloride waste, polyvinyl chloride waste, accelerator and solid halogen agent are mixed and calcined to obtain calcined material; the accelerator is iron waste; the solid halogen agent is at least one of carbonate, bicarbonate, basic oxide and basic hydroxide; the calcination temperature is 400-550℃ and the holding time is 40-80min.

[0026] The calcined material is mixed with water and subjected to solid-liquid separation to obtain a liquid material and a solid material; the solid material is a recovery accelerator.

[0027] The liquid material is crystallized to obtain recycled sodium chloride.

[0028] In this invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art or prepared using methods well known to those skilled in the art.

[0029] This invention involves mixing sodium chloride-containing waste, polyvinyl chloride (PVC) waste, an accelerator, and a solidifying agent, followed by calcination to obtain calcined material. In this invention, the mass fraction of sodium chloride in the sodium chloride-containing waste is preferably ≥85%, more preferably 90-95%. Preferably, the sodium chloride waste residue is dried to constant weight, and then the resulting dried material is pulverized to obtain the sodium chloride-containing waste. In this invention, the drying temperature is preferably 100-110°C. The pulverizing instrument used in this invention is preferably a grinding mill. The particle size of the sodium chloride-containing waste in this invention is preferably 80-200 mesh, more preferably 100-150 mesh.

[0030] In this invention, the mass fraction of chlorine in the polyvinyl chloride waste is preferably 50-70%, more preferably 57.3%. In this invention, the polyvinyl chloride waste preferably includes at least one of waste PVC water pipes and automotive PVC plastic, more preferably waste PVC water pipes. In this invention, the waste PVC water pipes preferably include at least one of aged PVC water pipes and broken PVC water pipes, more preferably broken PVC water pipes. In an embodiment of this invention, the waste PVC water pipes are specifically washed, dried, and pulverized sequentially; the washing reagent is distilled water; the drying is natural drying; and the pulverizing instrument is a ball mill. The particle size of the polyvinyl chloride waste in this invention is preferably 80-200 mesh, more preferably 100-150 mesh.

[0031] In this invention, the accelerator is iron-based waste; preferably, the accelerator includes at least one of hematite slag, chlorinated dust collector residue, iron slag, and metallurgical boiler residue, more preferably hematite slag or iron slag. The mass fraction of iron in the accelerator of this invention is preferably 1-30%, more preferably 10-28%, and more preferably 27%. The particle size of the accelerator of this invention is preferably 80-200 mesh, more preferably 100-150 mesh.

[0032] In this invention, the solidifying agent is at least one selected from carbonates, bicarbonates, basic oxides, and basic hydroxides; the carbonate is sodium carbonate and / or calcium carbonate, more preferably sodium carbonate; the bicarbonate is preferably sodium bicarbonate; the basic oxide is preferably sodium oxide and / or calcium oxide, more preferably sodium oxide; the basic hydroxide is preferably sodium hydroxide and / or potassium hydroxide, more preferably sodium hydroxide. In an embodiment of this invention, the solidifying agent is sodium hydroxide.

[0033] In this invention, the preferred mass ratio of the sodium chloride waste, polyvinyl chloride waste, and accelerator is 40–160:10–40:2–7, more preferably 60–90:15–25:3–5; the preferred molar ratio of chlorine in the polyvinyl chloride waste to the solid halogen agent is 1:0.5–1.5, more preferably 1:1–1.3, specifically 1:1, 1:1.1, 1:1.2, or 1:1.3. This invention preferably calculates the amount of chlorine based on the amount of polyvinyl chloride waste added and the mass fraction of chlorine in the polyvinyl chloride waste; taking Example 1 as an example, the amount of polyvinyl chloride waste added is 1.0000 g, and the mass fraction of chlorine in the polyvinyl chloride waste is 57.3%, the amount of chlorine is calculated as (1 × 57.3 / 35.5). This invention preferably calculates the amount of solid halogen agent based on the theory of complete absorption of chlorine in polyvinyl chloride waste. The calcination treatment described in this invention is preferably carried out in an air atmosphere; the air flow rate is preferably 80-150 mL / min, more preferably 100-120 mL / min. The calcination temperature is 400-550℃, preferably 420-500℃, more preferably 450-470℃; the holding time is 40-80 min, preferably 50-60 min. The calcination treatment is preferably carried out in a tube furnace. After the calcination treatment, the obtained material is preferably cooled to room temperature to obtain the calcined material. The cooling is preferably natural cooling.

[0034] After obtaining the calcined material, the present invention mixes the calcined material with water and performs solid-liquid separation to obtain liquid material and solid material. The preferred method of solid-liquid separation in the present invention is vacuum filtration. In the present invention, the solid material is a recovery accelerator. The recovery accelerator of the present invention can be reused in the calcination treatment step. Preferably, the recovery accelerator is dried before being reused in the calcination treatment step. The present invention does not have special requirements for the drying method and conditions; drying methods well known to those skilled in the art can be used.

[0035] After obtaining the liquid material, the present invention crystallizes the liquid material to obtain recovered sodium chloride. In the present invention, the crystallization is preferably performed by evaporation crystallization. The present invention does not have special requirements for the method and conditions of crystallization; crystallization methods well known to those skilled in the art can be used.

[0036] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] The sources and specifications of the sodium chloride-containing waste and polyvinyl chloride waste used in the examples are as follows:

[0038] Waste containing sodium chloride (source: sodium chloride residue, sodium chloride mass fraction: 92%, organic carbon (TOC) content: 3659 ppm);

[0039] Polyvinyl chloride waste (source: discarded PVC water pipes, Cl mass fraction: 57.3%);

[0040] Accelerator (hematite slag, iron mass fraction of 27%, particle size of 80-200 mesh).

[0041] Preparation Example 1

[0042] Sodium chloride waste residue was dried to constant weight at 105℃ and then ground to 80-200 mesh to obtain sodium chloride-containing waste.

[0043] Waste PVC water pipes are washed with distilled water, naturally dried, and then pulverized to 80-200 mesh using a ball mill to obtain waste polyvinyl chloride.

[0044] Example 1

[0045] The sodium chloride waste (4.0000 g), polyvinyl chloride waste (1.0000 g) obtained from Preparation Example 1, along with hematite slag (0.2000 g) and NaOH (0.7107 g, with a molar ratio of solid halogen agent to polyvinyl chloride waste of 1:1), were placed in a tube furnace and calcined at 470 °C for 50 min at an air flow rate of 100 mL / min. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain calcined material (4.6353 g).

[0046] The calcined material was mixed with water (100 mL) and filtered to obtain liquid and solid materials.

[0047] The solid material was washed with deionized water, dried, and then placed in a volumetric flask and diluted to 250 mL to obtain a solution. 1 mL of the solution was measured using a 1 mL pipette, and the chloride ion concentration (i.e., chloride content) in the solution was determined.

[0048] The liquid material is evaporated and crystallized to obtain recovered sodium chloride. The mass of the recovered sodium chloride is weighed, and the total organic carbon (TOC) content of the recovered sodium chloride is determined.

[0049] The results showed that the chlorine content in the solution was approximately 2.701 g, with a chlorine fixation rate of 98%; the recovered sodium chloride mass was 4.432 g, the regeneration rate of the regenerated sodium chloride was 121%, and the TOC content was 18.8 ppm.

[0050] The process flow diagram of the present invention is shown in Figure 1.

[0051] Example 2

[0052] The type of solid halogen agent was changed to NaHCO3, and the other conditions were the same as in Example 1, to obtain a solution and recover sodium chloride.

[0053] Example 3

[0054] The type of solid halogen agent was changed to Na2CO3, and the other conditions were the same as in Example 1, to obtain a solution and recover sodium chloride.

[0055] Example 4

[0056] The type of solid halogen agent was changed to KOH, and the other conditions were the same as in Example 1, to obtain a solution and recover sodium chloride.

[0057] Example 5

[0058] The type of solid halogen agent was changed to CaO, and the other conditions were the same as in Example 1, to obtain a solution and recover sodium chloride.

[0059] Example 6

[0060] The type of solid halogen agent was changed to CaCO3, and the other conditions were the same as in Example 1, to obtain a solution and recover sodium chloride.

[0061] The raw material composition, calcination conditions and product properties of Examples 1 to 6 are shown in Table 1.

[0062] Table 1. Raw material composition, calcination conditions, and product properties of Examples 1-6

[0063]

[0064]

[0065] Example 7

[0066] The molar ratio of solid halogen agent to polyvinyl chloride waste was adjusted to 1:1.1, and the remaining conditions were the same as in Example 1, to obtain a solution and recover sodium chloride.

[0067] Example 8

[0068] The molar ratio of solid halogen agent to polyvinyl chloride waste was adjusted to 1:1.2, and the remaining conditions were the same as in Example 1, to obtain a solution and recover sodium chloride.

[0069] Example 9

[0070] The molar ratio of solid halogen agent to polyvinyl chloride waste was adjusted to 1:1.3, and the remaining conditions were the same as in Example 1, to obtain a solution and recover sodium chloride.

[0071] The raw material composition, calcination conditions and product properties of Examples 33-35 are shown in Table 2.

[0072] Table 2. Raw material composition, calcination conditions, and product properties of Examples 7-9

[0073]

[0074] Comparative Example 1

[0075] The sodium chloride waste (4.0000 g) and polyvinyl chloride waste (1.0000 g) obtained in Preparation Example 1 were placed in a tube furnace and calcined at 450 °C for 60 min at an air flow rate of 100 mL / min. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain calcined material (3.5079 g).

[0076] The calcined material was mixed with deionized water (100 mL) and filtered to obtain liquid and solid materials.

[0077] The liquid material was transferred to a volumetric flask, and water was added to bring the volume to 250 mL to obtain a solution. The solution was then evaporated and crystallized to obtain recovered sodium chloride. The total organic carbon (TOC) content of the recovered sodium chloride was determined.

[0078] The results showed that the chlorine fixation rate in the solution was 0; the TOC content of the recovered sodium chloride was 502 ppm.

[0079] Comparative Example 2

[0080] The calcination conditions were adjusted to: calcination temperature of 410℃, holding time of 60 min, air flow rate of 100 mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0081] Comparative Example 3

[0082] The calcination conditions were adjusted to: calcination temperature of 430℃, holding time of 60 min, air flow rate of 100 mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0083] Comparative Example 4

[0084] The calcination conditions were adjusted to: calcination temperature of 470℃, holding time of 60 min, air flow rate of 100 mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0085] Comparative Example 5

[0086] The calcination conditions were adjusted to: calcination temperature of 490℃, holding time of 60min, air flow rate of 100mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0087] The raw material composition, calcination conditions and product properties of Comparative Examples 1 to 5 are shown in Table 3.

[0088] Table 3. Raw material composition, calcination conditions, and product properties of Comparative Examples 1–5

[0089]

[0090]

[0091] Comparative Example 6

[0092] The calcination conditions were adjusted as follows: holding time of 40 min, calcination temperature of 470℃, air flow rate of 100 mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0093] Comparative Example 7

[0094] The calcination conditions were adjusted as follows: holding time of 50 min, calcination temperature of 470℃, air flow rate of 100 mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0095] Comparative Example 8

[0096] The calcination conditions were adjusted as follows: holding time of 60 min, calcination temperature of 470℃, air flow rate of 100 mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0097] Comparative Example 9

[0098] The calcination conditions were adjusted as follows: holding time of 70 min, calcination temperature of 470℃, air flow rate of 100 mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0099] Comparative Example 10

[0100] The calcination conditions were adjusted as follows: holding time of 80 min, calcination temperature of 470℃, air flow rate of 100 mL / min, and other conditions were the same as those in Comparative Example 1, to obtain a solution and recover sodium chloride.

[0101] The raw material composition, calcination conditions and product properties of Comparative Examples 6–10 are shown in Table 4.

[0102] Table 4. Raw material composition, calcination conditions, and product properties of Comparative Examples 6–9

[0103]

[0104]

[0105] Comparative Example 11

[0106] The calcination conditions were adjusted to: air flow rate of 60 mL / min, calcination temperature of 470℃, and holding time of 50 min. The remaining conditions were the same as those in Comparative Example 1. A solution was obtained and sodium chloride was recovered.

[0107] Comparative Example 12

[0108] The calcination conditions were adjusted to: air flow rate of 80 mL / min, calcination temperature of 470℃, and holding time of 50 min. The remaining conditions were the same as those in Comparative Example 1. A solution was obtained and sodium chloride was recovered.

[0109] Comparative Example 13

[0110] The calcination conditions were adjusted to: air flow rate of 120 mL / min, calcination temperature of 470℃, and holding time of 50 min. The remaining conditions were the same as those in Comparative Example 1, resulting in the preparation of a solution and recovery of sodium chloride.

[0111] Comparative Example 14

[0112] The calcination conditions were adjusted to: air flow rate of 140 mL / min, calcination temperature of 470℃, and holding time of 50 min. The remaining conditions were the same as those in Comparative Example 1. A solution was obtained and sodium chloride was recovered.

[0113] The raw material composition, calcination conditions and product properties of Comparative Examples 11–14 are shown in Table 5.

[0114] Table 5. Raw material composition, calcination conditions, and product properties of Comparative Examples 11–14

[0115]

[0116] Comparative Example 15

[0117] The sodium chloride waste (4.0000 g) and polyvinyl chloride waste (1.0000 g) obtained in Preparation Example 1 were placed in a tube furnace and calcined at 470 °C for 50 min at an air flow rate of 100 mL / min. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain calcined material (3.6126 g).

[0118] The calcined material was mixed with water (100 mL) and filtered to obtain liquid and solid materials.

[0119] The liquid material was transferred to a volumetric flask, and water was added to bring the volume to 250 mL to obtain a solution. The solution was then evaporated and crystallized to obtain recovered sodium chloride. The total organic carbon (TOC) content of the recovered sodium chloride was determined.

[0120] The results showed that the chlorine fixation rate in the solution was 0; the TOC content of the recovered sodium chloride was 502 ppm, and the TOC removal rate was approximately 86.2%.

[0121] Comparative Example 16

[0122] The mass ratio of sodium chloride waste to polyvinyl chloride waste was adjusted to 16:1 (i.e., the mass of sodium chloride waste was 4.0000g and the mass of polyvinyl chloride waste was 0.2500g), and the other conditions were the same as those in Comparative Example 15, to obtain a solution and recover sodium chloride.

[0123] Comparative Example 17

[0124] The mass ratio of sodium chloride waste to polyvinyl chloride waste was adjusted to 8:1 (i.e., the mass of sodium chloride waste was 4.0000g and the mass of polyvinyl chloride waste was 0.5000g), and the remaining conditions were the same as those in Comparative Example 15, to obtain a solution and recover sodium chloride.

[0125] Comparative Example 18

[0126] The mass ratio of sodium chloride waste to polyvinyl chloride waste was adjusted to 2:1 (i.e., the mass of sodium chloride waste was 4.0000g and the mass of polyvinyl chloride waste was 2.0000g), and the other conditions were the same as those in Comparative Example 15, to obtain a solution and recover sodium chloride.

[0127] The raw material composition, calcination conditions and product properties of Comparative Examples 15–18 are shown in Table 6.

[0128] Table 6. Raw material composition, calcination conditions, and product properties of Examples 15-18

[0129]

[0130] Comparative Example 19

[0131] Sodium chloride waste (4.0000g), polyvinyl chloride waste (1.0000g), and CuBr2 (0.1500g, accounting for 3% of the total mass of sodium chloride waste and polyvinyl chloride waste) were placed in a tube furnace and calcined at 470℃ for 50min at an air flow rate of 100mL / min. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain calcined material (3.6942g).

[0132] The calcined material was mixed with water (100 mL) and filtered to obtain liquid and solid materials.

[0133] The liquid material is evaporated and crystallized to obtain recovered sodium chloride, and the total organic carbon (TOC) content of the recovered sodium chloride is determined.

[0134] The results showed that the TOC content of the recovered sodium chloride was 214 ppm.

[0135] Comparative Example 20

[0136] The type of accelerator was adjusted to FeCl3 (0.1500 g, accounting for 3% of the total mass of sodium chloride and polyvinyl chloride waste), and the other conditions were the same as those in Comparative Example 19, resulting in the recovery of sodium chloride.

[0137] Comparative Example 21

[0138] The type of accelerator was adjusted to MnSO4 (0.1500g, accounting for 3% of the total mass of sodium chloride and polyvinyl chloride waste), and the other conditions were the same as those in Comparative Example 19, resulting in the recovery of sodium chloride.

[0139] Comparative Example 22

[0140] The type of accelerator was adjusted to Cr2O3 (0.1500g, accounting for 3% of the total mass of sodium chloride and polyvinyl chloride waste), and the other conditions were the same as those in Comparative Example 19, resulting in the recovery of sodium chloride.

[0141] Comparative Example 23

[0142] The type of accelerator was adjusted to Ni2O3 (0.1500g, accounting for 3% of the total mass of sodium chloride and polyvinyl chloride waste), and the other conditions were the same as those in Comparative Example 19, resulting in the recovery of sodium chloride.

[0143] Comparative Example 24

[0144] The type of accelerator was adjusted to K2S2O8 (0.1500g, accounting for 3% of the total mass of waste containing sodium chloride and polyvinyl chloride), and the other conditions were the same as those in Comparative Example 19, resulting in the recovery of sodium chloride.

[0145] Comparative Example 25

[0146] The type of accelerator was adjusted to hematite slag (0.1500g, accounting for 3% of the total mass of sodium chloride-containing waste and polyvinyl chloride waste), and the other conditions were the same as those in Comparative Example 19, resulting in the recovery of sodium chloride.

[0147] Comparative Example 26

[0148] The type of accelerator was adjusted to chlorinated dust collector residue (0.1500g, accounting for 3% of the total mass of sodium chloride-containing waste and polyvinyl chloride waste), and the other conditions were the same as those in Comparative Example 19, resulting in the recovery of sodium chloride.

[0149] The raw material composition, calcination conditions and product properties of Comparative Examples 19–26 are shown in Table 7.

[0150] Table 7. Raw material composition, calcination conditions, and product properties of Comparative Examples 19–26

[0151]

[0152] Comparative Example 27

[0153] Sodium chloride waste (4.0000g), polyvinyl chloride waste (1.0000g), and hematite slag (0.1500g, accounting for 3% of the total mass of sodium chloride waste and polyvinyl chloride waste) were placed in a tube furnace and calcined at 470℃ for 50min with an air flow rate of 100mL / min. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain calcined material (3.7084g).

[0154] The calcined material was mixed with water (100 mL) and filtered to obtain liquid and solid materials.

[0155] The solid material is washed with deionized water, dried to obtain a reusable material, and then placed in a dryer for later use.

[0156] Transfer the liquid material to a volumetric flask, add water to bring the volume to 250 mL, and obtain a solution. Measure 1 mL of the solution using a 1 mL pipette and determine the chloride ion concentration (i.e., chloride content) in the solution.

[0157] The solution was evaporated and crystallized to obtain recovered sodium chloride, and the total organic carbon (TOC) content of the recovered sodium chloride was determined.

[0158] The results showed that the TOC content of the recovered sodium chloride was 32.2 ppm.

[0159] Comparative Example 28

[0160] The amount of hematite slag accelerator added was adjusted to 0.2000g (4% of the total mass of waste containing sodium chloride and polyvinyl chloride), and the other conditions were the same as those in Comparative Example 27, to obtain a solution and recover sodium chloride.

[0161] Comparative Example 29

[0162] The amount of hematite slag accelerator added was adjusted to 0.2500g (5% of the total mass of waste containing sodium chloride and polyvinyl chloride), and the other conditions were the same as those in Comparative Example 27, to obtain a solution and recover sodium chloride.

[0163] Comparative Example 30

[0164] The amount of accelerator hematite slag added was adjusted to 0.3000g (6% of the total mass of sodium chloride and polyvinyl chloride waste), and the other conditions were the same as those in Comparative Example 27, to obtain a solution and recover sodium chloride.

[0165] Comparative Example 31

[0166] The accelerator was adjusted to be a recycled material of hematite slag (i.e., a recovery accelerator), and the addition amount was 0.2000g (accounting for 4% of the total mass of sodium chloride-containing waste and polyvinyl chloride waste). The other conditions were the same as those in Comparative Example 27, and a solution and recovered sodium chloride were obtained.

[0167] The raw material composition, calcination conditions and product properties of Examples 27-31 are shown in Table 8.

[0168] Table 8. Raw material composition, calcination conditions, and product properties of Comparative Examples 27–31

[0169]

[0170] The results show that the resource recovery method provided by this invention can reduce the TOC content in recovered sodium chloride to 14.8–24.9 ppm, which is lower than the industrial treatment requirements. Simultaneously, the Cl fixation rate in polyvinyl chloride waste exceeds 98%, and the treatment temperature is significantly lower than that of existing technologies (600–700°C). The filtered residue can be reused. Furthermore, the resource recovery process of this invention does not generate waste gas, wastewater, or waste residue. While achieving the resource recovery of sodium chloride and polyvinyl chloride waste, it avoids the generation of secondary pollutants such as hydrogen chloride and dioxins, reducing environmental harm.

[0171] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for the resource-based treatment of waste containing sodium chloride and polyvinyl chloride, comprising the following steps: Waste containing sodium chloride, waste polyvinyl chloride, an accelerator, and a solidifying agent are mixed and calcined to obtain calcined material. The accelerator is iron waste. The solidifying agent is at least one of carbonate, bicarbonate, basic oxide, and basic hydroxide. The calcination temperature is 400–550°C, and the holding time is 40–80 min. The calcined material is mixed with water and subjected to solid-liquid separation to obtain liquid and solid materials. The solid material is a recovery accelerator. The liquid material is crystallized to obtain recovered sodium chloride.

2. The resource recovery method according to claim 1, characterized in that, The particle size of the sodium chloride waste, polyvinyl chloride waste, and accelerator is independently 80-200 mesh.

3. The resource recovery method according to claim 1, characterized in that, The sodium chloride content in the sodium chloride-containing waste is ≥85% by mass.

4. The resource recovery method according to claim 1, characterized in that, The chlorine content in the polyvinyl chloride waste is 50-70% by mass.

5. The resource recovery method according to claim 1 or 4, characterized in that, The polyvinyl chloride waste includes at least one of waste PVC water pipes and automotive PVC plastics.

6. The resource recovery method according to claim 1, characterized in that, The accelerator includes at least one of hematite slag, chlorinated dust collector slag, iron slag, and metallurgical boiler residue.

7. The resource recovery method according to claim 6, characterized in that, The accelerator contains 1-30% iron by mass.

8. The resource recovery method according to claim 1, characterized in that, The carbonate is sodium carbonate and / or calcium carbonate; the bicarbonate is sodium bicarbonate; the basic oxide is sodium oxide and / or calcium oxide; the basic hydroxide is sodium hydroxide and / or potassium hydroxide.

9. The resource recovery method according to claim 1, characterized in that, The mass ratio of the sodium chloride waste, polyvinyl chloride waste, and accelerator is 40–160:10–40:2–7; the molar ratio of chlorine and solid halogen agent in the polyvinyl chloride waste is 1:0.5–1.

5.

10. The resource recovery method according to claim 1, characterized in that, The calcination process is carried out in an air atmosphere with an air flow rate of 80–150 mL / min.

Images