Gold smelting wastewater treatment method

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly discloses a gold smelting wastewater treatment method which comprises the following steps: step 1, adding a chemical agent into gold smelting wastewater, and enabling ions in the chemical agent to quickly react with target pollutant ions in the wastewater; 2, along with the proceeding of the reaction, precipitate particles are gradually increased and increased; the particles can collide and gather with one another to form larger flocs; the sedimentation speed and the sedimentation effect are determined by the size and the density of the floc; 3, the wastewater is separated through a wastewater separation process, precipitates in the wastewater are separated, and the wastewater separation process adopts natural precipitation, flocculent precipitation or filtration assistance; step 4, carrying out subsequent treatment on the separated wastewater, wherein the subsequent treatment comprises precipitate treatment and detection and adjustment of effluent; the operation is simple, heavy metal pollutants in the wastewater can be effectively removed, and the recycling of precipitates can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for treating gold refining wastewater. Background Art

[0002] During the gold smelting process, a large amount of wastewater is generated, and its sources are wide-ranging, such as the filtrate after the zinc powder replacement of the gold-rich precious liquid in the cyanide gold extraction process. The wastewater contains cyanide, heavy metal ions (such as zinc, copper, lead, mercury, etc.), sulfate, chloride ions and other harmful substances.

[0003] If these wastewaters are discharged directly, they will cause serious environmental pollution, such as destroying water ecology, polluting soil, etc., endangering human health and ecological balance. At the same time, if the valuable metals (such as gold, silver, copper, etc.) and cyanide in the wastewater can be effectively recovered, resources can be reused and production costs can be reduced.

[0004] In order to reduce costs and facilitate implementation, current gold refining wastewater treatment methods usually choose chemical precipitation methods. However, current chemical precipitation methods are difficult to effectively remove heavy metal ions in wastewater, and there is a lack of methods for properly handling precipitated sludge. Summary of the invention

[0005] The purpose of the present invention is to provide a method for treating gold smelting wastewater to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for treating gold refining wastewater, comprising the following steps:

[0007] Step 1: Add chemical reagents to the gold smelting wastewater, and the ions in the reagents react rapidly with the target pollutant ions in the wastewater.

[0008] Step 2: As the reaction proceeds, the sediment particles gradually increase and grow larger; these particles will collide and aggregate with each other to form larger flocs; the size and density of the flocs determine their sedimentation speed and effect.

[0009] Step three: Separate the wastewater through a wastewater separation process to separate the sediment in the wastewater. The wastewater separation process uses natural sedimentation, flocculation sedimentation or filtration assistance.

[0010] Step 4: Perform subsequent treatment on the separated wastewater, which includes sediment treatment and effluent testing and adjustment.

[0011] As a preferred embodiment of the present invention, the chemical agent includes sodium hydroxide and calcium hydroxide; the selected chemical agent is added to the wastewater and stirred continuously during the addition process; after the chemical agent is added, it immediately reacts chemically with the target pollutants in the wastewater, and the hydroxide ions combine with the heavy metal ions to form insoluble hydroxide precipitates. These reactions are usually fast ion reactions, which can convert most of the target pollutants into precipitates in a short time.

[0012] As preferred in the present invention, the precipitated particles undergo a maturation process in the solution, during which small precipitated particles may collide and merge with each other to form larger and more stable particles, thereby improving the sedimentation performance of the precipitate; the length of the maturation time is affected by many factors, such as temperature, stirring speed, and the nature of the precipitate. Prolonging the maturation time appropriately helps to obtain a better precipitation effect, but it will also increase the processing time and cost.

[0013] As a preferred method of the present invention, the natural sedimentation is to rely on gravity to make the sediment sink to the bottom of the container naturally under static conditions to form a sedimentation layer. This method is simple, but the sedimentation speed may be slow, and is suitable for situations where the processing speed requirement is not high.

[0014] As a preferred method of the present invention, the flocculation precipitation is performed by adding a flocculant to the wastewater, wherein the flocculant includes polyacrylamide, and the flocculant can adsorb the sediment particles to form larger and more compact flocs, thereby accelerating the precipitation speed. Flocculation precipitation is usually used to improve the precipitation efficiency and shorten the processing time.

[0015] As a preferred embodiment of the present invention, the filtration aid may still contain a small amount of fine sediment particles in the supernatant after precipitation, which can be further removed by filtering with a filtering device. The filtering device uses a sand filter or an activated carbon filter, which can intercept solid particles in the wastewater and make the effluent clearer.

[0016] As a preferred embodiment of the present invention, the sediment treatment is to dehydrate and dry the precipitated sediment to reduce the water content. The treated sludge can be used to make building materials, soil conditioners or fertilizers. However, in the process of resource utilization, it must be ensured that the content of harmful substances in the sludge meets the relevant standards and will not cause harm to the environment and human health.

[0017] The dehydration includes placing the sludge in a centrifuge and separating the solid particles from the water in the sludge by the centrifugal force generated by high-speed rotation. The centrifugal dehydrator has the advantages of fast processing speed and small footprint, but the equipment investment and operating costs are relatively high.

[0018] The drying includes drying the dehydrated sludge if it is necessary to further reduce the water content or to make it reach a certain degree of dryness; the drying methods include natural drying (placing the sludge in a well-ventilated place and using natural sunlight and wind to dry it) and thermal drying (using hot air, steam or other heat sources to heat and dry the sludge).

[0019] As a preferred embodiment of the present invention, the detection and adjustment of the effluent, the effluent after chemical precipitation treatment is subjected to water quality monitoring, the water quality monitoring includes pH value, heavy metal ion concentration, chemical oxygen demand, biochemical oxygen demand and suspended solids. Through water quality monitoring, the water quality status of the effluent can be timely understood, and the dosage of chemical agents can be accurately calculated and adjusted according to the effluent water quality status to ensure that the pollutants can be fully removed.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention adds specific chemicals to wastewater to react with pollutants in the wastewater to generate insoluble precipitates. These precipitates can be separated from the wastewater by precipitation, filtration, etc., so as to achieve the purpose of removing pollutants. The operation is simple, the heavy metal pollutants in the wastewater can be effectively removed, and the precipitates can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] See also Figure 1 The present invention provides a technical solution: a method for treating gold refining wastewater, comprising the following steps:

[0025] Step 1: Add chemical reagents to the gold smelting wastewater, and the ions in the reagents react rapidly with the target pollutant ions in the wastewater.

[0026] Chemical agents include sodium hydroxide and calcium hydroxide; the selected chemical agents are added to the wastewater and stirred continuously during the addition process; after the chemical agents are added, they immediately react with the target pollutants in the wastewater, and the hydroxide ions combine with the heavy metal ions to form insoluble hydroxide precipitates. These reactions are usually fast ion reactions, which can convert most of the target pollutants into precipitates in a short time.

[0027] Step 2: As the reaction proceeds, the sediment particles gradually increase and grow larger; these particles will collide and aggregate with each other to form larger flocs; the size and density of the flocs determine their sedimentation speed and effect.

[0028] The precipitated particles will undergo a maturation process in the solution. During the maturation process, small particles may collide and merge with each other to form larger and more stable particles, thereby improving the sedimentation performance of the precipitate. The length of the maturation time is affected by many factors, such as temperature, stirring speed, and the nature of the precipitate. Prolonging the maturation time appropriately will help to obtain better precipitation effects, but it will also increase processing time and cost.

[0029] Step three: Separate the wastewater through a wastewater separation process to separate the sediment in the wastewater. The wastewater separation process uses natural sedimentation, flocculation sedimentation or filtration assistance.

[0030] Natural sedimentation, under static conditions, relies on gravity to make the sediment sink to the bottom of the container naturally to form a sedimentation layer. This method is simple, but the sedimentation speed may be slow, and it is suitable for situations where the processing speed is not required.

[0031] Flocculation sedimentation, adding flocculants to wastewater, including polyacrylamide, can adsorb sediment particles to form larger and more compact flocs, thereby accelerating the sedimentation rate. Flocculation sedimentation is usually used to improve sedimentation efficiency and shorten treatment time.

[0032] Filtration aids: After sedimentation, the supernatant may still contain a small amount of fine sediment particles, which can be further removed by filtering equipment. The filtering equipment uses sand filters or activated carbon filters, which can intercept solid particles in the wastewater and make the effluent clearer.

[0033] Influencing factors:

[0034] pH value: Different chemical precipitation reactions have specific requirements for pH value. For example, some metal ions can only form stable precipitation within a specific pH range. If the pH value is too high or too low, it may lead to incomplete precipitation or other side reactions. Therefore, in actual operation, the pH value of wastewater needs to be accurately adjusted to ensure the efficient precipitation reaction.

[0035] Types and dosage of chemical agents: Choosing the right chemical agent is the key. Different pollutants require different agents to react with them to form precipitation. Moreover, the dosage of the agent also needs to be strictly controlled. Too little dosage may not completely precipitate the pollutants; too much dosage will not only increase costs, but may also lead to difficulties in subsequent treatment, such as excessive precipitation sludge.

[0036] Reaction temperature: Temperature has a significant effect on the rate of chemical reactions. Within a certain range, increasing the temperature can speed up the precipitation reaction, but too high a temperature may cause some chemical agents to decompose or volatilize, affecting the precipitation effect. Therefore, it is necessary to select a suitable reaction temperature based on the specific reaction and agent characteristics.

[0037] Initial concentration of wastewater: The higher the initial concentration of pollutants in the wastewater, the greater the amount of chemicals required to form precipitation, and the precipitation process may be interfered by more factors. For high-concentration wastewater, pretreatment or multi-stage precipitation may be required to improve the treatment effect.

[0038] Step 4: Perform subsequent treatment on the separated wastewater, which includes sediment treatment and effluent testing and adjustment.

[0039] Sediment treatment, dehydration and drying of the settled sediment to reduce the water content. The treated sludge can be used to make building materials, soil conditioners or fertilizers. However, in the process of resource utilization, it is necessary to ensure that the content of harmful substances in the sludge meets the relevant standards and will not cause harm to the environment and human health.

[0040] Dehydration involves placing the sludge in a centrifuge, where the centrifugal force generated by high-speed rotation separates the solid particles from the water in the sludge. Centrifugal dehydrators have the advantages of fast processing speed and small footprint, but the equipment investment and operating costs are relatively high.

[0041] Drying includes drying the dehydrated sludge if it needs to further reduce the water content or reach a certain degree of dryness; drying methods include natural drying (placing the sludge in a well-ventilated area and using natural sunlight and wind to dry it) and thermal drying (using hot air, steam and other heat sources to heat and dry the sludge).

[0042] Testing and adjustment of effluent: water quality monitoring is carried out on effluent after chemical precipitation treatment. Water quality monitoring includes pH value, heavy metal ion concentration, chemical oxygen demand, biochemical oxygen demand and suspended solids. Through water quality monitoring, the effluent water quality status can be timely understood. According to the effluent water quality status, the dosage of chemical agents can be accurately calculated and adjusted to ensure that pollutants can be fully removed.

[0043] In summary, the present invention adds specific chemicals to wastewater to react with pollutants in the wastewater to generate insoluble precipitates. These precipitates can be separated from the wastewater by precipitation, filtration, etc., thereby achieving the purpose of removing pollutants. Using the principle of chemical reaction, adding chemicals to wastewater to convert harmful components into precipitates, thereby purifying wastewater, the operation is relatively simple, and pollutants such as heavy metals in wastewater can be effectively removed.

[0044] It is worth noting that the entire device is controlled by a main control button. Since the device matched with the control button is a common device and belongs to the existing mature technology, its electrical connection relationship and specific circuit structure will not be described in detail here.

[0045] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating gold refining wastewater, characterized in that: The following steps are involved: Step 1: Add chemical reagents to the gold smelting wastewater, and the ions in the reagents react rapidly with the target pollutant ions in the wastewater; Step 2: As the reaction proceeds, the sediment particles gradually increase and grow larger; these particles collide and aggregate with each other to form flocs; Step 3: Separate the wastewater by a wastewater separation process to separate the sediment in the wastewater. The wastewater separation process adopts natural sedimentation, flocculation sedimentation or filtration-assisted; Step 4: Perform subsequent treatment on the separated wastewater, which includes sediment treatment and effluent testing and adjustment.

2. A method for treating gold smelting wastewater according to claim 1, characterized in that: The chemical agents include sodium hydroxide and calcium hydroxide; the selected chemical agents are added into the wastewater and continuously stirred during the adding process; after the chemical agents are added, they immediately react chemically with the target pollutants in the wastewater, and the hydroxide ions combine with the heavy metal ions to form insoluble hydroxide precipitates.

3. The method for treating gold refining wastewater according to claim 1, characterized in that: The precipitated particles will undergo a maturation process in the solution. During the maturation process, small precipitated particles may collide and merge with each other to form larger and more stable particles, thereby improving the sedimentation performance of the precipitate.

4. The method for treating gold refining wastewater according to claim 1, characterized in that: The natural sedimentation, under static conditions, allows the sediment to naturally sink to the bottom of the container by gravity to form a sedimentation layer.

5. The method for treating gold smelting wastewater according to claim 1, characterized in that: The flocculation sedimentation is performed by adding a flocculant to the wastewater. The flocculant includes polyacrylamide. The flocculant can adsorb sediment particles to form larger and tighter flocs, thereby accelerating the sedimentation rate.

6. A method for treating gold smelting wastewater according to claim 1, characterized in that: The filtration aid may still contain a small amount of fine sediment particles in the supernatant after precipitation, which can be further removed by filtering with a filtering device; the filtering device adopts a sand filter or an activated carbon filter.

7. The method for treating gold refining wastewater according to claim 1, characterized in that: The sediment treatment is to dehydrate and dry the precipitated sediment to reduce the water content. The treated sludge can be used to make building materials, soil conditioners or fertilizers. The dehydration includes placing the sludge into a centrifuge and separating the solid particles and water in the sludge by the centrifugal force generated by high-speed rotation. The drying includes drying the dehydrated sludge if it is necessary to further reduce the water content or to make it reach a certain degree of dryness; the drying methods include natural drying and thermal drying.

8. The method for treating gold refining wastewater according to claim 1, characterized in that: The detection and adjustment of the effluent, the water quality monitoring of the effluent after chemical precipitation treatment, the water quality monitoring includes pH value, heavy metal ion concentration, chemical oxygen demand, biochemical oxygen demand and suspended solids. Through water quality monitoring, the water quality status of the effluent can be understood in time, and the dosage of chemical agents can be accurately calculated and adjusted according to the effluent water quality status to ensure that the pollutants can be fully removed.

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