Cyanide-containing wastewater treatment system for purifying calcium carbide furnace gas

Abstract

The utility model discloses a calcium carbide furnace gas purification cyanide-containing wastewater treatment system which comprises a water inlet tank, a water outlet of the water inlet tank is connected with a water inlet of a pH pre-adjusting tank, a water outlet of the pH pre-adjusting tank is connected with a water inlet of a cyanide removal reaction tank, and a water outlet of the cyanide removal reaction tank is connected with a water inlet of a flocculation tank. A water outlet of the flocculation tank is connected with a water inlet of the sedimentation tank, a water outlet of the sedimentation tank is connected with a water inlet of the pH readjusting tank, and a water outlet of the pH readjusting tank is connected with a water inlet of the water outlet tank. By adjusting the pH value of the cyanide-containing wastewater and adding ferric salt and PAM, cyanide is condensed, and the cyanide content of the wastewater is reduced through precipitation separation, so that the water inlet requirement of an AO pool biochemical system in subsequent treatment is met.

Description

Technical Field

[0001] The utility model relates to the field of wastewater treatment, in particular to a system for treating cyanide-containing wastewater by purifying calcium carbide furnace gas. Background Art

[0002] The process of producing methanol from calcium carbide furnace gas mainly requires the tail gas from the calcium carbide furnace to undergo pretreatment steps such as dust removal, oil removal, desulfurization, detoxification, and deoxygenation; then it is sent to the conversion step, where carbon monoxide reacts with water under the action of a catalyst to produce hydrogen and carbon dioxide, thereby reducing the carbon monoxide content and increasing the hydrogen content in the calcium carbide furnace gas; finally, the raw gas after decarbonization treatment is sent to the synthesis step to synthesize methanol.

[0003] In the actual production process, the pretreatment and conversion processes generate 15m3 / h of wastewater per hour. After the various wastewaters are mixed, they are temporarily stored in the accident pool. Then the wastewater in the accident pool is sent to the sewage treatment device. After the mixed wastewater and each wastewater are tested separately, the cyanide content of the mixed wastewater is about 450mg / L. Among them, the lowest cyanide content is 33.75mg / L in the conversion separator wastewater, and the highest cyanide content is 1937.14mg / L in the purification and regeneration wastewater, both exceeding the sewage anaerobic system water inlet index of 10mg / L. Exceeding chemical indicators will lead to sludge poisoning in the AO pool biochemical system of the sewage treatment device, exceeding the COD indicator will cause the AO pool biochemical system to be unable to treat, the COD indicator of the biochemical effluent will exceed the standard, and the grey water system will be unable to treat and reuse, affecting the operation of the entire sewage treatment device. Therefore, this part of cyanide-containing wastewater cannot directly enter the sewage treatment device, and this part of cyanide-containing wastewater can only be used as calcium carbide slag for ash casting, and finally as raw material for cement production. However, due to the certain consumption, this part of cyanide-containing wastewater cannot be consumed completely, which restricts the normal production of the calcium carbide furnace gas device. Utility Model Content

[0004] The utility model aims to provide a system for treating cyanide-containing wastewater by purifying calcium carbide furnace gas.

[0005] The utility model is implemented by the following technical solutions:

[0006] A system for treating cyanide-containing wastewater by purifying calcium carbide furnace gas, comprising a water inlet tank, wherein the drainage port of the water inlet tank is connected to the water inlet of a pH pre-adjusting tank, the water outlet of the pH pre-adjusting tank is connected to the water inlet of a cyanide removal reaction tank, the water outlet of the cyanide removal reaction tank is connected to the water inlet of a flocculation tank, the water outlet of the flocculation tank is connected to the water inlet of a sedimentation tank, the water outlet of the sedimentation tank is connected to the water inlet of a pH re-adjusting tank, and the water outlet of the pH re-adjusting tank is connected to the water inlet of a water outlet tank;

[0007] The water inlet of the water inlet tank is connected to the cyanide wastewater pipe; the dosing ports of the pH pre-adjustment tank and the pH re-adjustment tank are both connected to the alkali dosing pipe; the dosing port of the cyanide removal reaction tank is connected to the iron salt dosing pipe; the dosing port of the flocculation tank is connected to the PAM dosing pipe;

[0008] The water outlet of the sedimentation tank is also connected to the dosing port of the pH pre-adjusting tank through a reflux pipe, and a reflux pump is installed on the reflux pipe; a pH detector is installed in the pH pre-adjusting tank, and the signal output end of the pH detector is electrically connected to the signal input end of the reflux pump.

[0009] Preferably, the sludge discharge port of the sedimentation tank is connected to the inlet of a sludge delivery pump, and the outlet of the sludge delivery pump is connected to the inlet of a sludge thickening tank.

[0010] Preferably, the drain outlet of the water inlet tank is connected to the inlet of the lift pump, and the outlet of the lift pump is connected to the water inlet of the pH pre-adjustment tank.

[0011] The utility model has the advantages of: adjusting the pH of cyanide-containing wastewater, adding iron salt and PAM to condense cyanide, and reducing the cyanide content of the wastewater through precipitation separation to meet the water inlet requirement of the AO pool biochemical system in subsequent treatment; in the process of reducing the pH of cyanide-containing wastewater, the weakly acidic wastewater after condensation of cyanide is returned to the pH pre-adjusting tank, which can replace acid solution to participate in neutralization, fully utilize the characteristics of production materials in production, and reduce the salt content in the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 It is a structural schematic diagram of the utility model.

[0014] In the figure: water inlet tank 1, pH pre-adjustment tank 2, cyanide removal reaction tank 3, flocculation tank 4, sedimentation tank 5, pH re-adjustment tank 6, water outlet tank 7, cyanide-containing wastewater pipe 8, alkali dosing pipe 9, iron salt dosing pipe 10, PAM dosing pipe 11, reflux pipe 12, reflux pump 13, pH detector 14, sludge conveying pump 15, and lifting pump 16. DETAILED DESCRIPTION

[0015] like Figure 1As shown, a system for treating cyanide-containing wastewater by purifying calcium carbide furnace gas comprises a water inlet tank 1, the drain outlet of the water inlet tank 1 is connected to the water inlet of a pH pre-adjusting tank 2, the water outlet of the pH pre-adjusting tank 2 is connected to the water inlet of a pH pre-adjusting tank 3, the water outlet of the pH pre-adjusting tank 3 is connected to the water inlet of a flocculation tank 4, the water outlet of the flocculation tank 4 is connected to the water inlet of a sedimentation tank 5, the water outlet of the sedimentation tank 5 is connected to the water inlet of a pH re-adjusting tank 6, and the water outlet of the pH re-adjusting tank 6 is connected to the water inlet of a water outlet tank 7;

[0016] The water inlet of the water inlet tank 1 is connected to the cyanide wastewater pipe 8; the dosing ports of the pH pre-adjustment tank 2 and the pH re-adjustment tank 6 are both connected to the alkali dosing pipe 9; the dosing port of the pH pre-adjustment tank 3 is connected to the iron salt dosing pipe 10; the dosing port of the flocculation tank 4 is connected to the PAM dosing pipe 11;

[0017] The water outlet of the sedimentation tank 5 is also connected to the dosing port of the pH pre-adjustment tank 2 through a reflux pipe 12, and a reflux pump 13 is installed on the reflux pipe 12; a pH detector 14 is installed in the pH pre-adjustment tank 2, and the signal output end of the pH detector 14 is electrically connected to the signal input end of the reflux pump 13;

[0018] The cyanide wastewater in the accident pool is first sent to the water inlet tank 1 through the cyanide wastewater pipe 8 for temporary storage, and then sent to the pH pre-adjustment tank 2 to adjust the pH of the cyanide wastewater to 8; the cyanide wastewater in the pH pre-adjustment tank 2 enters the pH pre-adjustment tank 3 after the pH is adjusted, and ferrous chloride is added to the pH pre-adjustment tank 3 through the iron salt dosing pipe 10 and fully stirred, so that the ferrous chloride and cyanide react fully. The reaction equation is:

[0019] 6CN - +3Fe 2+ →Fe2[Fe(CN)6]↓;

[0020] Since the pH pre-adjustment tank 3 is always in a stirring condition, the generated reactants will enter the flocculation tank 4 together with the cyanide-containing wastewater in the pH pre-adjustment tank 3; in the flocculation tank 4, the PAM (polyacrylamide) agent is injected into the flocculation tank 4 through the PAM dosing pipe 11 and fully stirred, and the reactants generated in the pH pre-adjustment tank 3 in the wastewater are fully condensed into larger flocs, which are sent to the sedimentation tank 5 for precipitation along with the wastewater in the flocculation tank 4. The flocculants are precipitated to the bottom of the flocculation tank 4 to achieve the purpose of removing cyanide, and the wastewater is sent to the pH re-adjustment tank 6 by overflow, and alkali solution is added to the pH re-adjustment tank 6 through the alkali dosing pipe 9 and fully stirred to neutralize the wastewater that becomes acidic after adding ferrous salt, so as to ensure that the wastewater is neutral and meets the requirements of the subsequent treatment links; the neutralized wastewater is sent to the outlet tank 7 for temporary storage, and then sent to the subsequent treatment process;

[0021] In the process of pH pre-adjustment tank 2, in most cases, the cyanide-containing wastewater is acidic, and the alkali dosing pipe 9 provides alkali solution to adjust the pH of the acidic cyanide-containing wastewater to 8; when the cyanide-containing wastewater is alkaline, that is, when the pH detector 14 detects that the pH of the cyanide-containing wastewater is greater than 8.5, the reflux pump 13 is controlled by the control system (such as PLC or DCS system) to start, and the weakly acidic wastewater overflowing to the pH re-adjustment tank 6 is sent back to the pH pre-adjustment tank 2 through the reflux pipe 12 until the cyanide-containing wastewater in the pH pre-adjustment tank 2 drops to 8.5, so that there is no need to add acid solution separately, and the wastewater with pH changes in production can be fully utilized to reduce the salt content in the wastewater.

[0022] The sludge discharge port of the sedimentation tank 5 is connected to the inlet of the sludge conveying pump 15, and the outlet of the sludge conveying pump 15 is connected to the inlet of the sludge thickening tank. The sludge precipitated at the bottom of the sedimentation tank 5 is regularly discharged to the sludge thickening tank through the sludge conveying pump 15 for concentration, in preparation for subsequent treatment as solid waste.

[0023] The drain outlet of the water inlet tank 1 is connected to the inlet of the lifting pump 16, and the outlet of the lifting pump 16 is connected to the water inlet of the pH pre-adjusting tank 2. The lifting pump 16 can be used to adjust the amount of cyanide-containing wastewater sent to the pH pre-adjusting tank 2 to avoid overload operation of the system.

[0024] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for treating cyanide-containing wastewater by purifying calcium carbide furnace gas, characterized in that: It comprises a water inlet tank, the drain outlet of the water inlet tank is connected to the water inlet of the pH pre-adjusting tank, the water outlet of the pH pre-adjusting tank is connected to the water inlet of the cyanide removal reaction tank, the water outlet of the cyanide removal reaction tank is connected to the water inlet of the flocculation tank, the water outlet of the flocculation tank is connected to the water inlet of the sedimentation tank, the water outlet of the sedimentation tank is connected to the water inlet of the pH re-adjusting tank, and the water outlet of the pH re-adjusting tank is connected to the water inlet of the water outlet tank; The water inlet of the water inlet tank is connected to the cyanide wastewater pipe; the dosing ports of the pH pre-adjustment tank and the pH re-adjustment tank are both connected to the alkali dosing pipe; the dosing port of the cyanide removal reaction tank is connected to the iron salt dosing pipe; the dosing port of the flocculation tank is connected to the PAM dosing pipe; The water outlet of the sedimentation tank is also connected to the dosing port of the pH pre-adjusting tank through a reflux pipe, and a reflux pump is installed on the reflux pipe; a pH detector is installed in the pH pre-adjusting tank, and the signal output end of the pH detector is electrically connected to the signal input end of the reflux pump.

2. A system for treating cyanide-containing wastewater by purifying calcium carbide furnace gas according to claim 1, characterized in that: The sludge discharge port of the sedimentation tank is connected to the inlet of the sludge delivery pump, and the outlet of the sludge delivery pump is connected to the inlet of the sludge concentration tank.

3. A system for treating cyanide-containing wastewater by purifying calcium carbide furnace gas according to claim 1 or 2, characterized in that: The drain outlet of the water inlet tank is connected to the inlet of the lift pump, and the outlet of the lift pump is connected to the water inlet of the pH pre-adjusting tank.

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