CN110040805B

CN110040805B - Degassing tower for decyanation of cyanogen-containing liquid and recovery of valuable substances

Info

Publication number: CN110040805B
Application number: CN201910270211.XA
Authority: CN
Inventors: 胡长伟; 孙辰; 曹卫星; 赵永军; 张跃进
Original assignee: Jiaxing University
Current assignee: Jiaxing University
Priority date: 2019-04-04
Filing date: 2019-04-04
Publication date: 2021-07-16
Anticipated expiration: 2039-04-04
Also published as: CN110040805A

Abstract

The invention discloses a degassing tower for decyanation of cyanogen-containing liquid and recovery of valuable substances, which is provided with a closed space enclosed by a bottom plate, a tower wall and a tower top, wherein the tower top is provided with an exhaust port, the exhaust port is communicated with an absorption tower, the closed space in the degassing tower is divided into an aeration chamber and a circulation chamber by a partition plate, the upper part of the partition plate is provided with an overflow port, the lower part of the partition plate is provided with a circulation port, the bottom of the aeration chamber is provided with an aeration device, the tower wall on one side of the circulation chamber is provided with a liquid inlet and a liquid outlet. The device can realize the high-efficiency removal of the hydrogen cyanide in the cyanide-containing liquid at lower cost and is beneficial to the recovery of valuable substances.

Description

Degassing tower for decyanation of cyanogen-containing liquid and recovery of valuable substances

Technical Field

The invention belongs to the technical field of nonferrous metallurgy and environmental protection, and particularly relates to a degassing tower for decyanation of cyanogen-containing liquid and recovery of valuable substances.

Background

In gold smelting, a cyanidation method is mainly adopted at the present stage. The cyanidation method has a long history of being applied to gold extraction technology, has high recovery rate, simple technology and low unit cost, so the cyanidation method is adopted by most gold ores in the world. The cyanides used in cyanidation to leach gold are mainly potassium cyanide, sodium cyanide, calcium cyanide and ammonium cyanide, all of which are highly toxic compounds. In industrial production, a large amount of liquid is carried in tailings after cyaniding and gold extraction, the liquid contains a large amount of cyanide, great hidden danger is brought to the surrounding environment, and the cyanide also has higher value. In addition, the cyanide process waste liquid also contains nonferrous metals with high value, such as copper, zinc, silver and the like, and has high recovery value.

The recovery of cyanide and valuable metal in cyanide-containing waste liquid is carried out by acidification, i.e. sulfuric acid is used to regulate pH value of cyanide-containing waste liquid to make it acidic, cyanide is converted into HCN, and when gas is filled into the waste liquid, HCN is escaped into gas phase from liquid phase and taken away by gas flow, so that the gas carrying HCN is contacted with NaOH solution, and HCN and NaOH are reacted to produce NaCN, which is reused for gold leaching.

The acidification recovery method has been applied for more than sixty years, and the adopted HCN stripping equipment is mainly a packed tower until now. However, the existing packed tower has certain defects that the treatment cost is higher than the recovery value when the cyanide concentration is low, the cyanide content of the waste water obtained after stripping often cannot reach the standard, the waste water is required to be treated again for discharge, various substances contained in the cyanide-containing waste liquid cause the blockage of the packed tower, and liquid flooding and air resistance increase can be caused if the gas-liquid ratio in the packed tower is too large, so that the power consumption is increased, and the economic benefit is reduced.

Disclosure of Invention

In view of the current situation of the degassing tower in the prior art, a degassing tower with a novel structure is designed, and a very high decyanation rate can be achieved at a relatively reasonable cost by adopting a very high gas-liquid ratio.

Specifically, the invention adopts the following technical scheme:

a degassing tower for decyanation of cyanogen-containing liquid and recovery of valuable substances is characterized in that the degassing tower is provided with a closed space enclosed by a bottom plate, a tower wall and a tower top, the tower top is provided with an exhaust port for discharging hydrogen cyanide-containing gas, the exhaust port is communicated to an absorption tower through a pipeline, the closed space inside the degassing tower is divided into two parts by a partition plate, the space on one side of the partition plate is an aeration chamber, the space on the other side of the partition plate is a circulation chamber, the upper part of the partition plate is an overflow port, the lower part of the partition plate is provided with a circulation port for communicating the aeration chamber and the circulation chamber, the bottom of the aeration chamber is provided with an aeration device for filling high-pressure gas into the liquid in the aeration chamber, the tower wall on one side of the circulation chamber is provided with a liquid inlet and a liquid outlet, the liquid inlet is positioned on the lower part, the liquid outlet, for promoting the mixing of the liquid entering from the liquid inlet and the liquid in the circulating chamber.

Preferably, the bottom of the circulation chamber is lower than the bottom of the aeration chamber, thereby forming a settling chamber in the lower portion of the circulation chamber. More preferably, a discharge opening is provided in the column wall at the bottom of the settling chamber.

Preferably, the blades of the paddle device have openings therein.

Further preferably, the paddle means is mounted in the circulation chamber by support means provided on the partition or on the tower wall of the circulation chamber.

In a preferred scheme, the air inlet of the aeration device is connected with the air outlet of the absorption tower.

Preferably, a heating device is arranged in the partition plate. More preferably, the heating device is a steam heat exchange device.

The degassing tower has a novel structure, cannot be blocked, can adopt an extremely high gas-liquid ratio, fully utilizes the cavitation effect and has an obvious decyanation effect. For the cyanide-containing tailings with higher valuable substance content, valuable substances can be recovered in a degassing tower, the treatment process after recovery is simple and convenient, the valuable substances are recovered, the decyanated liquid is better treated, and for treatment measures, the process difficulty and the treatment cost can be reduced.

Drawings

FIG. 1 is a schematic diagram of the overall configuration of a degasser according to the present invention;

fig. 2 is a top view of a paddle arrangement in the circulation chamber.

In the figure: 1. a base plate; 2. a tower wall; 3. the tower top; 4. a partition plate; 5. an aeration chamber; 6. a circulation chamber; 7. a settling chamber; 8. a liquid inlet; 9. a liquid outlet; 10. an exhaust port; 11. an overflow port; 12. a circulation port; 13. a product discharge port; 14. an aeration device; 15. a paddle device; 16. the liquid level of the aeration chamber; 17. a circulation chamber liquid level; 18. (ii) a deposit; 19. a steam line; 20. a blade; 21. a shaft; 22. a ring body.

Detailed Description

The present invention will be described in further detail below with reference to the accompanying drawings.

The degassing tower is used as a main device for decyanation by an acidification method, the existing degassing tower mainly adopts a packed tower form, and the working efficiency of the degassing tower is influenced by various factors, such as the content of metal ions in waste liquid, the acid adding amount, the packing density, the stripping temperature, the gas-liquid ratio and the like. For a packed tower, the first factor to be considered for increasing the stripping efficiency is the liquid film thickness, and the liquid film thickness is related to the selection of the density and the size of a packing ring. One aspect of increasing the hydrogen cyanide removal rate is to increase the gas-liquid ratio, which then leads to a large increase in power consumption due to the increase in gas drag, thereby reducing overall economic benefits. In addition, the working efficiency of the packed tower is influenced by the content of metal ions in the waste liquid, the packed tower is easy to block due to high ion concentration, but the whole equipment construction cost is increased due to precipitation before stripping, and the poisoning risk of operators is greatly increased. The above reasons and others make it difficult to improve the stripping efficiency of the existing packed tower.

In view of the current state of the art, the present invention has developed a degasser of novel construction. Referring to FIG. 1, there is shown the overall structure of a degasser column of the present invention.

The degassing tower for decyanation of cyanogen-containing liquid and recovery of valuable substances has a closed space enclosed by a bottom plate 1, a tower wall 2 and a tower top 3, wherein the tower top is provided with a gas outlet 10 for discharging hydrogen-containing gas, and the gas outlet is communicated with an absorption tower through a pipeline. And (3) sending the acidified cyanide-containing liquid into a degassing tower, blowing high-pressure gas serving as carrier gas into the cyanide-containing liquid, forming bubbles when the carrier gas passes through the cyanide-containing liquid to carry away hydrogen cyanide in the liquid to form the hydrogen cyanide-containing carrier gas, discharging the hydrogen cyanide-containing carrier gas through an exhaust port 10, conveying the discharged hydrogen cyanide-containing gas into an absorption tower through a pipeline, recovering cyanide, and preferably returning the residual gas to the degassing tower to be recycled as the carrier gas.

The closed space in the degassing tower is divided into two parts by a partition plate 4, the space on one side of the partition plate is an aeration chamber 5, the space on the other side of the partition plate is a circulation chamber 6, the upper part of the partition plate is an overflow port 11, and the lower part of the partition plate is provided with a circulation port 12 communicating the aeration chamber and the circulation chamber. An aeration device 14 is installed at the bottom of the aeration chamber for charging high pressure gas, preferably exhaust gas from the absorption tower, into the liquid in the aeration chamber. A liquid inlet 8 and a liquid outlet 9 are arranged on the tower wall at one side of the circulating chamber, the liquid inlet is positioned at the lower part, the liquid outlet is positioned at the upper part, and the position of the liquid outlet is lower than the overflow port at the upper part of the clapboard. The liquid in the degassing tower device has the advantage of circular degassing, the acidified cyanide-containing waste liquid enters the tower from the liquid inlet, hydrogen cyanide is removed in the aeration chamber through aeration, the cyanide flows into the circulation chamber from the overflow port and overflows from the liquid outlet, and the removal of the hydrogen cyanide is realized. The device changes the one-way flow form of the packed tower, does not adopt packing in the tower, can adopt extremely high gas-liquid ratio, does not block in the tower, has no influence of blocking on liquid flow, greatly improves the removal efficiency and controls the power consumption.

It is further preferred that the bottom of the circulation chamber is lower than the bottom of the aeration chamber so that a settling chamber 7 is formed in the lower part of the circulation chamber, in which settling chamber the liquid flow is relatively gentle, and insoluble matter in the acidified waste liquid can settle down to form a sediment in the bottom, and the sediment is discharged to the outside of the column through a discharge port 13 provided in the bottom wall of the settling chamber, thereby recovering valuable metals. Because the degassing tower adopts the design of circulating liquid flow, the blockage can not be generated, and the waste liquid entering the tower does not need to be precipitated in advance. Partial precipitation separation can be carried out in the tower, which is also beneficial to the treatment of discharged liquid and provides possibility for reducing the construction cost of the whole treatment facility. And (4) carrying out filter pressing and drying on the discharged precipitate to obtain a filter cake, wherein the separated liquid is cyanogen-containing liquid and is merged into a degassing procedure.

The acidified cyanide-containing waste liquid entering from the liquid inlet is mixed with the aerated waste liquid overflowing from the overflow port into the circulation chamber in the circulation chamber. In practice, however, there may be a separation between the two liquids in the circulation chamber, the waste liquid entering from the inlet with a higher cyanogen concentration being distributed along the wall of the column, and the aerated waste liquid entering from the overflow being distributed along the partition. To facilitate mixing of the two liquids, a paddle arrangement 15 is preferably mounted in the circulation chamber. Referring to figure 2, the paddle arrangement has vanes 20 and a shaft 21, the vanes being mounted to the shaft 21 by means of rings 22, and support means are provided on the partition or tower wall of the circulation chamber whereby the paddle arrangement is mounted in the circulation chamber. The blades of the paddle device have inclination angles and can slowly rotate in the circulating chamber under the action of water flow, so that the mixing of liquid in the circulating chamber is promoted. In another preferred embodiment, the blades of the paddle device are not complete blades, but have openings in the blades to increase turbulence formation in the circulation chamber and to promote mixing of the liquid.

The stripping action of hydrogen cyanide depends on the diffusion of gas, and increasing the stripping temperature increases the vapor pressure of hydrogen cyanide, which is more likely to escape from the liquid phase into the gas phase. In addition, the viscosity of the waste liquid can be reduced by increasing the temperature, and the speed of expanding the hydrogen cyanide to a gas phase through the interface of the liquid and the gas is increased. It is therefore advantageous to install a heating device in the degassing column as a preference. Preferably, the heating device is installed in the partition. More preferably, the heating device is a steam heat exchange device. As shown in FIG. 1, a steam pipe is installed in the partition plate so that the partition plate is integrally formed as a steam heat exchanger, and the temperature of the waste liquid can be adjusted by adjusting the throughput of steam.

The degassing column of the present invention can employ extremely high gas to liquid ratios, i.e., gas to liquid volume ratios, such as gas to liquid ratios of at least 300-. Waste gas discharged from an exhaust port of the absorption tower is pressed into the aeration chamber through the aeration device by the high-pressure pump, the waste liquid after full aeration overflows into the circulation chamber from the overflow port, the liquid on the upper layer is discharged out of the tower through the liquid outlet for further treatment, and the liquid on the lower layer is mixed with the acidified waste liquid entering through the liquid inlet. The extremely high gas-liquid ratio can bring faster liquid flow circulation speed, and the liquid is fully circulated in the tower, so that the hydrogen cyanide contained in the liquid is fully removed. If the cyanide content detected at the liquid outlet exceeds the preset standard, the gas-liquid ratio can be further increased, and the amount of waste liquid entering the liquid inlet is reduced until the waste liquid discharged from the liquid outlet meets the requirement. The paddle device rotates under the action of the liquid flow, the liquid flow flows downwards in the circulating chamber in the rotating direction, the upper degassed liquid flow and the cyanide-containing waste liquid entering from the lower part are separated, and the cyanide-containing waste liquid is prevented from being discharged from the liquid outlet along with the degassed liquid flow. And in the lower half part of the paddle device, turbulent flow is formed in the circulating chamber along with the rotation of the paddle device, so that the cyanogen-containing waste liquid and the decyanation waste liquid are mixed. According to the principle, the degassing tower can be suitable for cyanogen-containing waste liquid with wider cyanogen concentration range. For waste liquid with high cyanogen concentration, the cyanogen content of the liquid flow entering the aeration chamber can be reduced by mixing the waste liquid with the decyanation liquid flow in the circulation chamber, and the hydrogen cyanide contained in the waste liquid can be removed cleanly by increasing the aeration amount, improving the circulation speed and the circulation times. And for the waste liquid with less cyanogen content, the aeration quantity can be reduced, so that the power consumption is reduced, and better economic efficiency is realized.

While the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.

Claims

1. A degassing tower for decyanation of cyanogen-containing liquid and recovery of valuable substances is characterized in that the degassing tower is provided with a closed space enclosed by a bottom plate, a tower wall and a tower top, the tower top is provided with an exhaust port for discharging hydrogen cyanide-containing gas, the exhaust port is communicated to an absorption tower through a pipeline, the closed space inside the degassing tower is divided into two parts by a partition plate, the space on one side of the partition plate is an aeration chamber, the space on the other side of the partition plate is a circulation chamber, the upper part of the partition plate is an overflow port, the lower part of the partition plate is provided with a circulation port for communicating the aeration chamber and the circulation chamber, the bottom of the aeration chamber is provided with an aeration device for filling high-pressure gas into the liquid in the aeration chamber, the tower wall on one side of the circulation chamber is provided with a liquid inlet and a liquid outlet, the liquid inlet is positioned on the lower part, the liquid outlet, the bottom of the circulating chamber is lower than the bottom of the aeration chamber, so that a settling chamber is formed at the lower part of the circulating chamber, and a discharge port is arranged on the tower wall at the bottom of the settling chamber.

2. The degasifier for decyanation of cyanogen-containing liquid and recovery of valuable materials according to claim 1, wherein the blades of the paddle means have openings.

3. A degasser column as claimed in claim 1, wherein the paddle means is mounted in the circulation chamber by means of support means provided on the partition or the wall of the circulation chamber.

4. The degassing tower for decyanation of cyanide-containing liquid and recovery of valuable substances according to claim 1, wherein the gas inlet of the aeration device is connected to the gas outlet of the absorption tower.

5. The degasifier according to claim 1, wherein the partition is provided with a heating device.

6. The degasser column used for decyanation of cyanogen-containing liquids and recovery of valuable materials as claimed in claim 5, wherein said heating means is a steam heat exchanger.