Method of purifying sodium bromide from waste circuit boards pyrolysis coke

Abstract

A method for producing and purifying sodium bromide using the coke from waste circuit boards pyrolysis residues as reducing agent, belonging to the field of purifying sodium bromide and high-value utilization, and more particularly, relating to a method for reducing and purifying crude bromine salt obtained from waste circuit boards smelting ash by using the coke in waste circuit boards pyrolysis residues. The main steps are as follows: carbonization conversion, water dissolution, filtration, and concentrated crystallization under vacuum heating. The pure sodium bromide was obtained by reducing crude bromine salt enriched from waste circuit board smelting ash by using the coke in waste circuit boards pyrolysis residues, realizing the resource coupling and high-value utilization of the two wastes, avoiding the secondary pollution in the process of recycling the waste circuit boards. It has the characteristics of simple operation, high resource utilization rate and no tail liquid discharge.

Claims

1. A method for producing and purifying sodium bromide using coke from waste circuit boards pyrolysis residues as reducing agent, characterized by the following specific steps: (1) carbonization conversion: crude bromine salt is mixed with the coke separated from the waste circuit boards pyrolysis residues to obtain a mixture; the crude bromide salt is a by-product obtained from waste circuit boards smelting ash through sulphating roasting-alkali washing-neutralization precipitation and evaporation crystallization, which contains NaBr, NaBrO and NaBrO.sub.3; the mixture is heated to obtain carbon monoxide and a primary product of sodium bromide containing NaBr and C from the coke; the carbon monoxide is collected and used as raw material of water gas; during mixing, the mass of the coke is 0.1˜1.0 kg per kilogram of the crude bromine salt, the temperature is 250˜450° C., and the time is 1.0˜2.0 h; (2) water dissolution and filtration: the primary product of sodium bromide obtained in step (1) is added to distilled water for dissolution and filtration to obtain insoluble impurities which contain C and NaBr which contains leachate; (3) concentrated crystallization under vacuum heating: the NaBr obtained in step (2) is concentrated and crystallized by vacuum heating to obtain sodium bromide (NaBr); this step is carried out in a vacuum evaporation device, which includes an evaporator, a solvent collecting tank and a vacuum system; the evaporator is communicated with the solvent collecting tank and the vacuum system respectively, a condenser and a material head tank are arranged on the evaporator and respectively communicated with the same, and the vacuum system is communicated with the condenser and the solvent collecting tank respectively, so that pressure in the condenser can be kept balanced with that of the solvent colleting tank and liquefied solvent in the condenser flows into the solvent collecting tank automatically.

2. A method for producing and purifying sodium bromide using the coke from waste circuit boards pyrolysis residues as reducing agent according to claim 1, characterized in that, during the water dissolution and filtration, a liquid-solid volume/mass ratio of distilled water to the primary product of sodium bromide is 8:1˜3:1 (L/kg), the temperature is 50˜80° C., and the time is 20˜60 min.

3. A method for producing and purifying sodium bromide using the coke from waste circuit boards pyrolysis residues as reducing agent according to claim 1, characterized in that, during the concentrated crystallization, the time is 30˜60 min and the temperature is 60˜150° C.

Description

DESCRIPTION OF DRAWINGS

[0013] FIG. 1 shows the process flow diagram of obtaining crude bromine salt from waste circuit board smelting ash.

[0014] FIG. 2 shows the process flow diagram of obtaining the coke from waste circuit boards pyrolysis residues.

[0015] FIG. 3 shows the process flow diagram of producing and purifying sodium bromide using the coke from waste circuit boards pyrolysis residues as reducing agent.

EXEMPLARY EMBODIMENTS

[0016] The following exemplary embodiments are intended to further illustrate the invention rather than limit it.

Exemplary Embodiment 1

[0017] The recovery steps are as follows:

[0018] (1) Carbonization conversion: the crude bromine salt is mixed with the coke separated from the waste circuit boards pyrolysis residues to obtain a mixture. The crude bromide salt is a by-product obtained from waste circuit boards smelting ash through sulphating roasting-alkali washing-neutralization precipitation and evaporation crystallization, which contains NaBr, NaBrO and NaBrO.sub.3. Then the mixture is heated to obtain carbon monoxide and the primary product of sodium bromide (containing NaBr and C from coke). The carbon monoxide is collected and used as raw material of water gas. During mixing, the mass of the coke is 0.1 kg per kilogram of crude bromine salt, the temperature is 250° C., and the time is 1.0 h;

[0019] (2) Water dissolution and filtration: the primary product of sodium bromide obtained in step (1) is added to distilled water for dissolution and filtration to obtain insoluble impurities (containing C) and NaBr-containing leachate. During the water dissolution and filtration, the liquid-solid volume mass ratio (distilled water to primary product of sodium bromide) is 8:1 (L/kg), the temperature is 50° C., and the time is 20 min;

[0020] (3) Concentrated crystallization under vacuum heating: the NaBr-containing leachate obtained in step (2) is concentrated and crystallized by vacuum heating to obtain sodium bromide (NaBr). During the concentrated crystallization, the time is 60 min and the temperature is 60° C. This step is carried out in a vacuum evaporation device, which includes an evaporator, a solvent collecting tank and a vacuum system. The evaporator is communicated with the solvent collecting tank and the vacuum system respectively, a condenser and a material head tank are arranged on the evaporator and respectively communicated with the same, and the vacuum system is communicated with the condenser and the solvent collecting tank respectively, so that pressure in the condenser can be kept balanced with that of the solvent colleting tank and liquefied solvent in the condenser flows into the solvent collecting tank automatically.

[0021] The purity of the obtained sodium bromide is 98.6%, which meets the standard of the first grade sodium bromide (NaBr≥98.5%) in the standard HG/T 3809-2006 of State Ministry of Chemical Industry.

Exemplary Embodiment 2

[0022] The recovery steps are as follows:

[0023] (1) Carbonization conversion: the crude bromine salt is mixed with the coke separated from the waste circuit boards pyrolysis residues to obtain a mixture. The crude bromide salt is a by-product obtained from waste circuit boards smelting ash through sulphating roasting-alkali washing-neutralization precipitation and evaporation crystallization, which contains NaBr, NaBrO and NaBrO.sub.3. Then the mixture is heated to obtain carbon monoxide and the primary product of sodium bromide (containing NaBr and C from coke). The carbon monoxide is collected and used as raw material of water gas. During mixing, the mass of the coke is 1.0 kg per kilogram of crude bromine salt, the temperature is 450° C., and the time is 2.0 h;

[0024] (2) Water dissolution and filtration: the primary product of sodium bromide obtained in step (1) is added to distilled water for dissolution and filtration to obtain insoluble impurities (containing C) and NaBr-containing leachate. During the water dissolution and filtration, the liquid-solid volume mass ratio (distilled water to primary product of sodium bromide) is 3:1 (L/kg), the temperature is 80° C., and the time is 60 min;

[0025] (3) Concentrated crystallization under vacuum heating: the NaBr-containing leachate obtained in step (2) is concentrated and crystallized by vacuum heating to obtain sodium bromide (NaBr). During the concentrated crystallization, the time is 30 min and the temperature is 150° C. This step is carried out in a vacuum evaporation device, which includes an evaporator, a solvent collecting tank and a vacuum system. The evaporator is communicated with the solvent collecting tank and the vacuum system respectively, a condenser and a material head tank are arranged on the evaporator and respectively communicated with the same, and the vacuum system is communicated with the condenser and the solvent collecting tank respectively, so that pressure in the condenser can be kept balanced with that of the solvent colleting tank and liquefied solvent in the condenser flows into the solvent collecting tank automatically.

[0026] The purity of the obtained sodium bromide is 99.4%, which meets the standard of the superior product sodium bromide (NaBr≥99%) in the standard HG/T 3809-2006 of State Ministry of Chemical Industry.

Exemplary Embodiment 3

[0027] The recovery steps are as follows:

[0028] (1) Carbonization conversion: the crude bromine salt is mixed with the coke separated from the waste circuit boards pyrolysis residues to obtain a mixture. The crude bromide salt is a by-product obtained from waste circuit boards smelting ash through sulphating roasting-alkali washing-neutralization precipitation and evaporation crystallization, which contains NaBr, NaBrO and NaBrO.sub.3. Then the mixture is heated to obtain carbon monoxide and the primary product of sodium bromide (containing NaBr and C from coke). The carbon monoxide is collected and used as raw material of water gas. During mixing, the mass of the coke is 0.4 kg per kilogram of crude bromine salt, the temperature is 300° C., and the time is 1.2 h;

[0029] (2) Water dissolution and filtration: the primary product of sodium bromide obtained in step (1) is added to distilled water for dissolution and filtration to obtain insoluble impurities (containing C) and NaBr-containing leachate. During the water dissolution and filtration, the liquid-solid volume mass ratio (distilled water to primary product of sodium bromide) is 7:1 (L/kg), the temperature is 60° C., and the time is 25 min;

[0030] (3) Concentrated crystallization under vacuum heating: the NaBr-containing leachate obtained in step (2) is concentrated and crystallized by vacuum heating to obtain sodium bromide (NaBr). During the concentrated crystallization, the time is 50 min and the temperature is 100° C. This step is carried out in a vacuum evaporation device, which includes an evaporator, a solvent collecting tank and a vacuum system. The evaporator is communicated with the solvent collecting tank and the vacuum system respectively, a condenser and a material head tank are arranged on the evaporator and respectively communicated with the same, and the vacuum system is communicated with the condenser and the solvent collecting tank respectively, so that pressure in the condenser can be kept balanced with that of the solvent colleting tank and liquefied solvent in the condenser flows into the solvent collecting tank automatically.

[0031] The purity of the obtained sodium bromide is 98.8%, which meets the standard of the first grade sodium bromide (NaBr≥98.5%) in the standard HG/T 3809-2006 of State Ministry of Chemical Industry.

Exemplary Embodiment 4

[0032] The recovery steps are as follows:

[0033] (1) Carbonization conversion: the crude bromine salt is mixed with the coke separated from the waste circuit boards pyrolysis residues to obtain a mixture. The crude bromide salt is a by-product obtained from waste circuit boards smelting ash through sulphating roasting-alkali washing-neutralization precipitation and evaporation crystallization, which contains NaBr, NaBrO and NaBrO.sub.3. Then the mixture is heated to obtain carbon monoxide and the primary product of sodium bromide (containing NaBr and C from coke). The carbon monoxide is collected and used as raw material of water gas. During mixing, the mass of the coke is 0.8 kg per kilogram of crude bromine salt, the temperature is 400° C., and the time is 1.8 h;

[0034] (2) Water dissolution and filtration: the primary product of sodium bromide obtained in step (1) is added to distilled water for dissolution and filtration to obtain insoluble impurities (containing C) and NaBr-containing leachate. During the water dissolution and filtration, the liquid-solid volume mass ratio (distilled water to primary product of sodium bromide) is 6:1 (L/kg), the temperature is 75° C., and the time is 50 min;

[0035] (3) Concentrated crystallization under vacuum heating: the NaBr-containing leachate obtained in step (2) is concentrated and crystallized by vacuum heating to obtain sodium bromide (NaBr). During the concentrated crystallization, the time is 40 min and the temperature is 130° C. This step is carried out in a vacuum evaporation device, which includes an evaporator, a solvent collecting tank and a vacuum system. The evaporator is communicated with the solvent collecting tank and the vacuum system respectively, a condenser and a material head tank are arranged on the evaporator and respectively communicated with the same, and the vacuum system is communicated with the condenser and the solvent collecting tank respectively, so that pressure in the condenser can be kept balanced with that of the solvent colleting tank and liquefied solvent in the condenser flows into the solvent collecting tank automatically.

[0036] The purity of the obtained sodium bromide is 99.2%, which meets the standard of the superior product sodium bromide (NaBr≥99%) in the standard HG/T 3809-2006 of State Ministry of Chemical Industry.

Exemplary Embodiment 5

[0037] The recovery steps are as follows:

[0038] (1) Carbonization conversion: the crude bromine salt is mixed with the coke separated from the waste circuit boards pyrolysis residues to obtain a mixture. The crude bromide salt is a by-product obtained from waste circuit boards smelting ash through sulphating roasting-alkali washing-neutralization precipitation and evaporation crystallization, which contains NaBr, NaBrO and NaBrO.sub.3. Then the mixture is heated to obtain carbon monoxide and the primary product of sodium bromide (containing NaBr and C from coke). The carbon monoxide is collected and used as raw material of water gas. During mixing, the mass of the coke is 0.5 kg per kilogram of crude bromine salt, the temperature is 350° C., and the time is 1.5 h;

[0039] (2) Water dissolution and filtration: the primary product of sodium bromide obtained in step (1) is added to distilled water for dissolution and filtration to obtain insoluble impurities (containing C) and NaBr-containing leachate. During the water dissolution and filtration, the liquid-solid volume mass ratio (distilled water to primary product of sodium bromide) is 4:1 (L/kg), the temperature is 70° C., and the time is 40 min;

[0040] (3) Concentrated crystallization under vacuum heating: the NaBr-containing leachate obtained in step (2) is concentrated and crystallized by vacuum heating to obtain sodium bromide (NaBr). During the concentrated crystallization, the time is 45 min and the temperature is 120° C. This step is carried out in a vacuum evaporation device, which includes an evaporator, a solvent collecting tank and a vacuum system. The evaporator is communicated with the solvent collecting tank and the vacuum system respectively, a condenser and a material head tank are arranged on the evaporator and respectively communicated with the same, and the vacuum system is communicated with the condenser and the solvent collecting tank respectively, so that pressure in the condenser can be kept balanced with that of the solvent colleting tank and liquefied solvent in the condenser flows into the solvent collecting tank automatically.

[0041] The purity of the obtained sodium bromide is 98.9%, which meets the standard of the first grade sodium bromide (NaBr≥98.5%) in the standard HG/T 3809-2006 of State Ministry of Chemical Industry.

Exemplary Embodiment 6

[0042] The recovery steps are as follows:

[0043] (1) Carbonization conversion: the crude bromine salt is mixed with the coke separated from the waste circuit boards pyrolysis residues to obtain a mixture. The crude bromide salt is a by-product obtained from waste circuit boards smelting ash through sulphating roasting-alkali washing-neutralization precipitation and evaporation crystallization, which contains NaBr, NaBrO and NaBrO.sub.3. Then the mixture is heated to obtain carbon monoxide and the primary product of sodium bromide (containing NaBr and C from coke). The carbon monoxide is collected and used as raw material of water gas. During mixing, the mass of the coke is 0.6 kg per kilogram of crude bromine salt, the temperature is 350° C., and the time is 16 h;

[0044] (2) Water dissolution and filtration: the primary product of sodium bromide obtained in step (1) is added to distilled water for dissolution and filtration to obtain insoluble impurities (containing C) and NaBr-containing leachate. During the water dissolution and filtration, the liquid-solid volume mass ratio (distilled water to primary product of sodium bromide) is 5:1 (L/kg), the temperature is 70° C., and the time is 45 min;

[0045] (3) Concentrated crystallization under vacuum heating: the NaBr-containing leachate obtained in step (2) is concentrated and crystallized by vacuum heating to obtain sodium bromide (NaBr). During the concentrated crystallization, the time is 30 min and the temperature is 80° C. This step is carried out in a vacuum evaporation device, which includes an evaporator, a solvent collecting tank and a vacuum system. The evaporator is communicated with the solvent collecting tank and the vacuum system respectively, a condenser and a material head tank are arranged on the evaporator and respectively communicated with the same, and the vacuum system is communicated with the condenser and the solvent collecting tank respectively, so that pressure in the condenser can be kept balanced with that of the solvent colleting tank and liquefied solvent in the condenser flows into the solvent collecting tank automatically.

[0046] The purity of the obtained sodium bromide is 99.1%, which meets the standard of the superior product sodium bromide (NaBr≥99.0%) in the standard HG/T 3809-2006 of State Ministry of Chemical Industry.

[0047] The above embodiments are only used to illustrate the preferred embodiments of the invention, but the invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art and on the premise of not departing from the science and design spirit in the invention, the modifications, equivalent substitutions and improvements et al. made on the spirit and principles of the invention shall be regarded as in the scope of protection of the application.