CN117945595A - A process and system for low-carbon treatment of high-turbidity mine water - Google Patents

Abstract

The invention relates to a process and a system for low-carbon treatment under a high-turbidity mine well, wherein the process comprises the steps of collecting mine underground production sewage into a water collecting tank, feeding the sewage into a coal slime dehydration device through a lifting pump for mud-water separation, and enabling the obtained coal slime and separated water to flow into an intermediate water tank; delivering the separated water of the middle water tank to heavy medium speed submerged treatment equipment, and adding a coagulating agent to obtain clear water and sludge water; when a goaf is arranged under the coal mine, sludge water in the sludge pond is conveyed to the goaf through a sludge pump, and after natural filtration and interception of the goaf, the filtered water flows back to the water collecting pond; when the goaf is not arranged in the underground coal mine, sludge water in the sludge pond is conveyed to a filter press for filter pressing through a sludge pump, and the filter pressed coal cake is conveyed to a main conveying belt or a mine car for external conveying for coal cake recovery through a belt. The process and the system for treating the low carbon in the high turbidity mine water well provided by the invention have the advantages of wide application range, high efficiency, small occupied area, strong impact resistance, good economical efficiency, easiness in monitoring and management and the like.

Description

A process and system for low-carbon treatment of high-turbidity mine water

Technical Field

The invention relates to a process and a system for low-carbon treatment of high-turbidity mine water underground, belonging to the technical field of mine water treatment underground in coal mines.

Background technique

For the treatment of high-turbidity mine water, traditional processes such as horizontal flow sedimentation tanks, inclined plate/tube sedimentation tanks, mechanical accelerated clarification tanks, etc., are inconvenient to implement and operate due to their disadvantages such as low treatment efficiency, low load impact resistance, low sludge concentration, large sludge volume, high dosage of reagents, and large footprint (if arranged in underground tunnels, the disadvantages are more prominent). Traditional flocculation sedimentation tanks often occupy a large area, high-density inclined plate sedimentation tanks have a complex structure and occupy a large area, and high-efficiency cyclone purifiers have a large dosage of reagents and poor resistance to water quality fluctuations.

The upgraded process of the traditional coagulation and sedimentation process is the magnetic separation process. Its basic treatment route is: sedimentation tank + pre-sedimentation adjustment tank + coagulation tank + reaction tank + magnetic separation host + magnetic separation drum machine + sludge transfer tank + sludge tank + filter press device, but it has the following disadvantages:

(1) Suspended matter handling capacity and shock load resistance

The concentration of suspended solids in underground coal mine wastewater is high and fluctuates greatly, which places strict requirements on the impact load resistance of the process and equipment. Due to the technical defects of solid-liquid separation in the magnetic separation process, it cannot be used normally in the case of high suspended solids greater than 1000mg/L and large changes, and the stability of the effluent water quality cannot be guaranteed.

(2) Recovery rate of coagulation medium

The suspended solids concentration in underground coal mine wastewater is high and fluctuates greatly. The magnetic powder recovery rate of the magnetic separation process will be greatly reduced at a high concentration of SS ≥ 600 mg/L, and the amount of additional addition will be large; the recovery rate of the coagulation medium is poor.

(3) Impact on subsequent deep processing technology

The concentration of suspended solids in underground coal mine wastewater is high and fluctuates greatly. The magnetic powder recovery rate of the magnetic separation process at high concentration will be greatly reduced, and the PAM dosage will be greatly increased. The lost magnetic powder and excess PAM reagent will enter the water tank with the produced water, making it more difficult to clear the tank; the wear of the lifting pump and piping system is also more obvious; after being lifted to the deep treatment unit on the ground, it will eventually lead to a greatly increased scaling tendency of the subsequent deep treatment membrane (the main reason why many mines are replacing this process), which is not conducive to the normal operation of the subsequent system and the compliance of the produced water with the standard; the leaked magnetic powder may cause the subsequent deep treatment membrane material to be cut.

(4) Operating costs

The dosage of PAC and PAM is large, the magnetic separation recovery rate is low and is greatly affected by the incoming water quality, and the operating cost is high.

(5) Automation level of process system

Since the magnetic separation process uses a decentralized unit setting, it is not conducive to the system achieving unmanned or less-manned automation requirements.

(6) The process system is complicated and requires large one-time investment.

Summary of the invention

1. Technical issues to be resolved

In order to solve the above problems in the prior art, the present invention provides a process and system for underground low-carbon treatment of high-turbidity mine water.

(II) Technical solution

In order to achieve the above object, the main technical solutions adopted by the present invention include:

A process for low-carbon treatment of high-turbidity mine water underground, comprising the following steps:

S1. Collect the underground mine wastewater into the water collection tank, and then supply the wastewater to the coal slime dehydration device through the lifting pump for mud and water separation. The coal slime and separated water are transported to the main conveying belt by belt, and the separated water flows to the intermediate water tank by gravity;

S2. Send the separated water from the intermediate water tank to the heavy medium sedimentation treatment equipment, and add coagulant to obtain clean water and sludge water;

S3. When there is a goaf in the coal mine, the sludge water in the sludge pool is transported to the goaf through the sludge pump. After natural filtration and interception in the goaf, the filtered water flows back to the water collection tank by gravity;

When there is no goaf in the coal mine, the sludge water in the sludge pool is transported to the filter press by the sludge pump. The coal cakes after filtration are transported to the main transport belt or mine car by belt for coal cake recovery.

In the treatment process as described above, preferably, the coagulant comprises polyaluminium chloride and polyacrylamide, wherein polyaluminium chloride is added at 70-80 mg/L and polyacrylamide is added at 1.1-1.5 mg/L.

In the treatment process as described above, preferably, the coagulant also includes micro-sand, the particle size of the micro-sand is 100-150 μm, and the addition amount is 10 g/L; when the raw coal slime water contains a large number of particles with a particle size and specific gravity similar to those of micro-sand, they play the role of micro-sand to a certain extent, and the corresponding micro-sand addition amount should be appropriately reduced.

A system for low-carbon treatment of high-turbidity mine water underground, preferably, it comprises a water collection tank, a raw water lifting pump, a coal sludge dehydration device, an intermediate water tank, a heavy medium lifting pump, a heavy medium rapid water treatment device, a sludge tank and a sludge lifting pump connected in sequence, wherein the heavy medium rapid water treatment device is provided with a coagulation tank, an injection tank, a maturation tank and a sedimentation tank with a mud scraper adjacent in sequence, the height of the partition between the coagulation tank and the injection tank is lower than the height of the periphery of the coagulation tank, that is, the upper ends of the coagulation tank and the injection tank are connected, the lower end of the partition between the injection tank and the maturation tank is connected, and the mud scraper The machine is arranged at the upper end of the sedimentation tank, the lower end of the sedimentation tank is connected to a reflux pump, the reflux pump is connected to a sand-water separator, the sand outlet of the sand-water separator is connected to the upper end of the injection tank through a pipeline, and the mud outlet of the sand-water separator is connected to a sludge tank; the coagulation tank, injection tank and maturation tank are all provided with stirring paddles, and a clean water outlet is opened at the upper end of the sedimentation tank; the clean water outlet is also connected to a clean water tank, when there is a goaf in the coal mine, the sludge pipe of the sludge lifting pump is connected to one end of the existing goaf, and the other end of the existing goaf is connected to a water collection tank through the sludge pipe.

In the treatment system as described above, preferably, the water collection tank, the intermediate water tank, the recycled water tank and the sludge tank are configured as reinforced concrete structures, wherein the bottom planes of the water collection tank and the intermediate water tank are provided with a slope of 6° to 12°.

In the treatment system as described above, preferably, the heavy medium submersion treatment equipment is a square skid-mounted carbon steel structure, the raw water lift pump and the heavy medium lift pump are dry pumps, and the sludge pump is a slurry pump.

The treatment system as described above, preferably, when there is no goaf in the coal mine, the treatment system also includes a plate and frame filter press, the sludge lifting pump is connected to the inlet of the plate and frame filter press through the sludge pipe, and the liquid outlet of the plate and frame filter press is connected to the water collection tank through the sludge pipe.

In the treatment system as described above, preferably, the connecting pipe between the water collection tank and the heavy medium lifting pump is an underground production sewage pipe, and the clean water outlet and the clean water tank are connected by a clean water pipe; the heavy medium rapid sinking treatment equipment, the sludge tank and the sludge lifting pump are connected by a sludge pipe.

The treatment system as described above is preferably provided with ultrasonic level meters at the upper ends of the water collection tank, the intermediate water tank, the clear water tank and the sludge tank; manual butterfly valves are provided at both ends of each lifting pump, flexible joints are provided between the manual butterfly valve and the lifting pump, a pressure gauge and a check valve are provided at the water outlet of each lifting pump, and a flow meter is provided between the heavy medium lifting pump and the water inlet of the heavy medium rapid submersion treatment equipment.

The treatment system as described above preferably further comprises a PAC dosing device and a PAM dosing device, wherein the PAC dosing device is connected to the water inlet of the heavy medium velocity submersion treatment equipment, and the PAM dosing device is connected to the upper end of the maturation tank.

(III) Beneficial effects

The beneficial effects of the present invention are:

The process and system for low-carbon treatment of high-turbidity mine water provided by the present invention have the advantages of wide application range, high efficiency, small footprint, strong impact resistance, good economy, easy monitoring and management, etc. Compared with traditional reagents, the reagent usage of the process is lower, thereby achieving low-carbon treatment.

The underground low-carbon treatment process and system for high-turbidity mine water provided by the present invention also have the following advantages:

(1) It has good load compatibility and can stably handle suspended solids in influent with SS ≤ 12000 mg/L. It has strong adaptability to water quality. It has strong suspended solids processing capacity and impact load resistance.

(2) In the process of the present invention, the amount of micro-sand added is very small, and the sand particles in the incoming water have a suitable particle size and specific gravity, and can also properly serve as a micro-sand medium. There is no need to add micro-sand, and the recovery rate of the coagulation medium is high.

(3) In the process of the present invention, the dosage of PAM added is relatively small, which minimizes the impact on the subsequent deep processing unit.

(4) Compared with magnetic separation, the present invention can save 1/3 of the PAC and 3/4 of the PAM dosage; can recycle 99% of the micro-sand, can adopt an integrated and highly automated design to reduce labor cost investment; and has lower operating costs than magnetic separation.

(5) The equipment of the present invention is a skid-mounted equipment, which integrates a processing unit and an automatic control system, has a high degree of automation, and is easy to operate.

(6) The underground low-carbon treatment process for high-turbidity mine water provided by the present invention is simple and easy to manage, which greatly reduces the amount of civil engineering and mine construction and reduces the one-time investment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a preferred process flow for treating high-turbidity mine water with low carbon underground according to the present invention;

FIG2 is a schematic diagram of an underground low-carbon treatment process system for high-turbidity mine water according to an embodiment of the present invention;

FIG3 is a schematic diagram of the structure of a heavy medium velocity sinking treatment device;

FIG4 is a schematic diagram of the flocculation reaction process;

Figure 5 shows the flocs formed after ripening;

Figure 6 is a schematic diagram of the actual operation.

Detailed ways

After various high-turbidity mine water flows into the water tank, a large amount of coal and rock particles, mud, mortar and silt are deposited at the bottom of the tank, which will affect the safe and efficient production of coal mines underground. Frequent cleaning is required, and the traditional method of clearing the tank is labor-intensive and energy-intensive. The underground low-carbon treatment process for high-turbidity mine water provided by the present invention utilizes the micro-sand flocculation circulation technology of the heavy medium speed sinking water treatment equipment to treat the high-turbidity water on-site underground, and the treated clean water flows to the water tank by gravity, and the water tank is no longer silted, which completely solves the problem of clearing the tank and reduces the high-turbidity water lifting, etc., which reduces a lot of energy consumption.

The term "highly turbid mine water" in the present invention refers to the original clear groundwater in the mine that is polluted during the coal mining process.

In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

Example 1

A process for low-carbon treatment of high-turbidity mine water underground, the treatment process is divided into three units: coal slime dehydration, heavy medium rapid sedimentation, and sludge disposal. The specific process flow is shown in Figure 1, where:

(1) Coal slime dehydration unit

Highly turbid water from the mine is collected in a collection tank, and the sewage, i.e. raw water, is supplied to the coal slime dehydration device through a lifting pump for mud-water separation to remove coal slime particles with a particle size of ≥ 0.3 mm in the mine water. The coal slime is transported to the main transport belt (or transported out by mine car) through a belt, and the separated water flows by gravity to the intermediate water tank.

(2) Heavy medium water treatment unit

The intermediate water tank is equipped with a lifting pump to supply the water in the intermediate water tank to the heavy medium sedimentation treatment equipment. By adding polyaluminium chloride (PAC) and polyacrylamide (PAM) coagulants, suspended small particles such as coal powder can be further removed through coagulation and precipitation to obtain clean water and sludge water. Among them, PAC is added at a concentration of 80mg/L, PAM is added at a concentration of 1.1mg/L, and micro sand is added to make the micro sand as the crystal nucleus of floccules. The characteristics of micro sand with high specific gravity are used to accelerate the sedimentation rate of floccules. Micro sand is added at 10g/L. When the raw coal sludge water contains a large number of particles with particle size and specific gravity similar to micro sand, it can play the role of micro sand to a certain extent, and the corresponding micro sand addition amount can be appropriately reduced. The clean water treated by the equipment is collected by the pipeline (or water collection channel) and flows to the central water tank by gravity for storage. It is directly reused in production underground or lifted to the ground for external discharge through reuse (or external discharge pump).

The sludge water containing a large amount of suspended matter settled from the equipment flows by gravity into the sludge tank.

(3) Sludge disposal unit

There are two options for sludge disposal.

Option 1: When there is a goaf in the coal mine, the sludge water in the sludge pool is transported to the goaf through a sludge pump. After natural filtration and interception in the goaf, the filtered water flows back to the collection tank by gravity.

Option 2: When there is no goaf in the coal mine, the sludge water in the sludge pool is transported to the filter press by the sludge pump for filtration, and the coal cakes after filtration are transported to the main conveyor belt (or transported by mine car) by belt for coal cake recovery. The filtrate produced by the filter press is collected by gravity into the water collection tank for circulation treatment.

The water treatment system can also be equipped with online monitoring level meters, flow meters, automatic valves and remote video monitoring and control systems to achieve remote monitoring of sludge tanks, dosing tank levels, system processing flow and other related data, as well as remote equipment start and stop and valve switching.

The SS of high-turbidity mine water is ≤12000mg/L. After treatment with the above process, the SS of the clean water in the collection tank is ≤30mg/L.

Example 2

A system for low-carbon treatment of high-turbidity mine water underground, as shown in Figure 2, includes a water collection tank, a raw water lifting pump, a coal sludge dehydration device, an intermediate water tank, a heavy medium lifting pump, a heavy medium rapid water treatment device, a sludge tank and a sludge lifting pump connected in sequence. The heavy medium rapid water treatment device is provided with a coagulation tank, an injection tank, a maturation tank and a sedimentation tank with a scraper adjacent to each other in sequence. The height of the partition between the coagulation tank and the injection tank is lower than the height of the outer periphery of the coagulation tank. The lower part of the partition between the injection tank and the maturation tank is connected. The scraper is arranged at the upper end of the sedimentation tank. The lower end of the sedimentation tank is connected to a reflux pump, which is connected to a sand-water separator. The sand outlet of the sand-water separator is connected to the upper end of the injection tank through a pipeline, and the mud outlet of the sand-water separator is a sludge tank; the coagulation tank, the injection tank and the maturation tank are all provided with stirring paddles, and the upper end of the sedimentation tank is provided with a clean water outlet; the clean water outlet is also connected to a clean water tank, and the lower end of the clean water tank is also connected to an external discharge pump. When there is a goaf in the coal mine, the sludge pipe of the sludge lifting pump is connected to one end of the goaf, and the other end of the goaf is connected to the water collection tank through the sludge pipe. The connection between each device is connected through a pipeline. Furthermore, the connecting pipeline between the water collection tank and the heavy medium lifting pump is the underground production sewage pipe, and the clean water outlet and the clean water tank are connected by a clean water pipe; the heavy medium rapid submersion treatment equipment, the sludge tank and the sludge lifting pump are connected by a sludge pipe.

When there is no goaf in the coal mine, a plate and frame filter press is also installed. The sludge lifting pump is connected to the inlet of the plate and frame filter press through the sludge pipe, and the liquid outlet of the plate and frame filter press is connected to the water collection tank through the sludge pipe.

Specifically, the main parameter specifications of the above main equipment can be seen in Table 1 below.

Table 1

The structures that require reinforced concrete structures are shown in Table 2.

Table 2 List of main structures

The core treatment equipment of the underground low-carbon treatment process for high-turbidity mine water is the heavy medium rapid sedimentation treatment equipment, which is developed by integrating the "micro-sand flocculation circulation technology". It is very similar to the principle of traditional coagulation and sedimentation water treatment technology, using coagulants for destabilization, high molecular weight flocculants to aggregate suspended matter, and inclined plate (tube) sedimentation to remove suspended matter.

The improvement of this technology is to add micro-sand to quickly form flocs with micro-sand as the core, so that the flocs have the characteristics of high density, heavy weight and easy sedimentation. After sedimentation, the sludge with micro-sand is separated by a cyclone, the micro-sand is recovered, and the sludge flows to the sludge pool and is filtered.

The heavy medium velocity sedimentation treatment equipment integrates flocculation, sedimentation, micro-sand recovery and other functions. It is a highly integrated skid-mounted equipment with the characteristics of small size, high treatment efficiency and high degree of automation. The structure and working principle of the heavy medium velocity sedimentation treatment equipment are as follows: The overall equipment is a square skid-mounted carbon steel structure, which consists of five parts: the primary reaction zone, the secondary reaction zone, the tertiary reaction zone, the sedimentation zone, micro-sand recovery and sludge removal, and is equipped with chemical dosing and automatic control systems. Its structural schematic diagram is shown in Figure 3.

(1) Primary reaction zone (coagulation tank)

The natural particles that cause turbidity in the raw water are negatively charged and repel each other, thus forming a highly stable state. In order to remove them, coagulants (aluminum salts or iron salts) must first be added to the inlet pipeline and added to the coagulation tank to destabilize these particles. The kinetic process of coagulation is very short, and the coagulant achieves rapid and complete diffusion in the coagulation tank through rapid mechanical stirring.

(2) Secondary reaction zone (injection tank)

Micro sand with a particle size of about 100-150 μm is added to the secondary reaction zone and the reaction is accelerated by stirring. At the same time, the micro sand is continuously circulated to increase the probability of coagulation and ensure suitable flocs to increase their growth rate and weight.

(3) Tertiary reaction zone (maturation tank)

PAM is added to the maturation tank. The purpose of this tertiary reaction zone is to form large flocs. Flocculation is a physical and mechanical process that enhances the growth of flocs due to intermolecular forces and physical stirring. The addition of anionic polymer electrolytes can enhance floc formation through adsorption, electrical neutralization and bridging between particles.

Due to the accelerated flocculation of micro-sand, under the same sedimentation performance, its velocity gradient is equivalent to more than 8 times that of the traditional flocculation process. Under the condition of limited stirring time and limited flocculation volume, the high flocculation dynamic effect leads to an increase in the probability of collision between particles. Gentle stirring of the water body prevents the flocs from being broken. Although the stirring intensity in this stage is less than that in the previous coagulation stage, it is enough to keep the flocs suspended. The flocculation reaction process is shown in Figure 4, and the flocs formed after maturation are shown in Figure 5. The actual operation is shown in Figure 6, and it can be seen that clear water is finally formed.

(4) Sedimentation area (sedimentation tank)

After the tertiary reaction, the water enters the bottom of the sedimentation tank and then flows upward from the bottom of the inclined tube to the channel. Particles and flocs settle on the wall of the inclined tube and slide to the bottom of the tank under the action of gravity.

The rising velocity (surface load) in the sedimentation area is 40-60m/h, which is more than 6 times that of conventional sedimentation tanks. The improvement of sedimentation effect is based on: the alum flowers with micro sand as the core are dense and heavy; each sedimentation tank is equipped with honeycomb inclined pipes, and the reverse flow inclined pipe system increases the sedimentation area. Each sedimentation tank is equipped with honeycomb inclined pipes.

The design adopts a larger radial velocity. At the same time, due to the 60-degree inclination of the inclined tube, the sedimentation area is increased, which is more conducive to the sedimentation of sludge. Due to the installation of the sludge scraper, it can operate continuously to prevent the sludge from settling and hardening on the wall of the sludge bucket. The alum flocs produced after the tertiary reaction have a large density and are easy to settle. Most of the sludge has settled even before entering the inclined tube area, so the inclined tube in the sedimentation area does not need to be frequently flushed.

(5) Micro-sand recovery and sludge removal

The sludge containing micro-sand and accelerated sedimentation is settled at the bottom of the pool, and the scraper scrapes the sedimented micro-sand and sludge mixture into the central pit. The sludge return pump continuously extracts the mixture concentrated in the central pit.

A. Separation of micro sand and sludge

The reflux pump transports the micro sand and sludge to the sand-water separator. The sand-water separator uses the centrifugal principle to separate the micro sand from the sludge and directly add the separated micro sand to the secondary reaction area. The sludge overflows from the upper part of the sand-water separator and flows into the sludge pool through the sludge pipe.

B. Sludge system

The sand-water separator can ensure the efficient separation of micro-sand and sludge. The micro-sand lost by overflow from the sand-water separator is very small (about 1%), and this loss can be supplemented manually at regular intervals according to the scale of the system (such as before the end of each 8-hour operation shift). The discharged sludge contains a small amount of micro-sand, which will not have a special impact on the properties and treatment of the sludge. The sludge can be conventionally concentrated and dehydrated. (6) Chemical dosing

The chemical agents needed by the equipment mainly include polyaluminium chloride, anionic polyacrylamide, etc., and the consumables are micro sand. The equipment can automatically control the dosage through the dosing device according to the characteristics of the influent water quality to achieve economical operation.

(7) Automatic control system

The equipment is operated by PLC automatic control, thus reducing labor intensity, saving dosage and lowering operation cost. The automatic control system includes: flow, liquid level, pressure and other monitoring; operation control and operation conditions of mixer and sand return pump; inlet and outlet water quality monitoring to realize interlocking control and monitoring; specifically, ultrasonic level gauges are provided at the upper ends of water collection tank, intermediate water tank, clear water tank and sludge tank; manual butterfly valves are provided at both ends of each lifting pump, and flexible joints are provided between the manual butterfly valve and the lifting pump. Pressure gauges and check valves are also provided at the outlet end of each lifting pump. A flow meter is also provided between the heavy medium lifting pump and the water inlet of the heavy medium speed sinking treatment equipment. PAC dosing device and PAM dosing device are also provided. The PAC dosing device is connected to the water inlet of the heavy medium speed sinking treatment equipment, and the PAM dosing device is connected to the upper end of the maturation tank. The PAC dosing device includes a PAC dosing tank and a dosing pump; the PAM dosing device includes a PAM dosing tank and a dosing pump.

The heavy medium sedimentation treatment equipment can be set with specific parameters according to the needs. The equipment parameter selection can be seen in Table 3.

Table 3 Heavy medium velocity water treatment equipment selection table

Device Model AGPW-1 AGPW-2 AGPW-3 AGPW-4 AGPW-5 AGPW-6 AGPW-7 Processing capacity (m ³ /h) 100 200 300 400 500 600 700 Length(m) 5.82 7.5 8.42 9.48 10.5 11.31 14.85 Width(m) 2.28 3 3.22 3.6 3.8 4.32 4.32 Height(m) 2.6 2.8 3.1 3.2 3.6 4 3.8 First stage stirring(kW) 1.1 1.5 3 3 3 3 3 Secondary stirring (kW) 1.1 1.5 3 3 3 3 3 Three-stage stirring (kW) 1.5 2.2 5.5 5.5 5.5 5.5 5.5 Mud scraper (kW) 0.37 0.55 0.55 0.55 0.55 0.55 0.55*2 Sand return pump (kW) 4*2 5.5*2 7.5*2 7.5*2 7.5*2 7.5*2 7.5*4 Total power (kW) 12.07 16.75 27.05 27.05 27.05 27.05 42.6

The process and system for underground low-carbon treatment of high-turbidity mine water provided by the present invention have the following advantages:

1. Wide range of applications

It is suitable for all kinds of difficult water sources, including low-temperature and low-turbidity water. It can effectively remove algae, color, heavy metals, TOC, phosphorus, and COD.

2. High efficiency

The rising flow rate (surface load) is 40-60m/h, and the efficiency is more than 6 times that of conventional sedimentation tanks.

3. Small footprint

The area occupied is much smaller than that of conventional sedimentation tanks, about one-fourth of that of traditional processes. It is particularly suitable for projects with limited land or for renovation and expansion projects. If the equipment is set underground, its advantages are more obvious.

4. Strong impact resistance

When the raw water flow, turbidity and temperature fluctuate greatly, the heavy medium equipment can still stably and reliably guarantee the effluent quality. It can stably treat wastewater with suspended solids concentration SS less than 12000mg/L.

5. High economic efficiency

The investment in civil engineering and equipment is relatively small, and the cost of chemicals is saved, which can effectively reduce the operating costs by more than 1/3.

6. Easy to monitor and manage

It can enter a stable operating state in a very short time (usually less than 10 minutes); it integrates automatic control of turbidity, liquid level, pH, dosing, stirring, heavy medium recovery, etc., which is easy to monitor and manage.

7. Wide application in the industry

Heavy medium submersible water treatment equipment can be widely used in municipal and industrial water supply, sewage and wastewater, recycled water treatment, river and lake management and other occasions, including coal mining, electric power, papermaking, chemical industry, electronics and river purification.

The underground low-carbon treatment process for high-turbidity mine water of the present invention is compared with existing processes such as flocculation inclined tube sedimentation process, high-density sedimentation tank process, high-efficiency cyclone purification process, and magnetic separation process. The results are shown in Table 4.

Table 4 Process comparison

As can be seen from the above, traditional processes such as horizontal flow sedimentation tanks, inclined plate/tube sedimentation tanks, mechanical accelerated clarification tanks, etc., due to their low treatment efficiency, low load impact resistance, low sludge concentration, large sludge volume, high dosage of reagents, and large footprint, are inconvenient to implement and operate (the disadvantages are more prominent when arranged in underground tunnels). Traditional flocculation sedimentation tanks often occupy a large area, high-density inclined plate sedimentation tanks have a complex structure and occupy a large area, and high-efficiency cyclone purifiers have large dosages of reagents and poor resistance to water quality fluctuations.

The upgraded process of traditional coagulation and sedimentation process - magnetic separation and micro-sand heavy medium rapid sedimentation process has obvious advantages and characteristics. The process is compared from the following six aspects:

(1) Suspended matter handling capacity and shock load resistance.

The concentration of suspended solids in underground coal mine wastewater is high and fluctuates greatly, which places strict requirements on the impact load resistance of the process and equipment. Due to the technical defects of the solid-liquid separation stage of the magnetic separation process, it cannot be used normally under the conditions of high suspended solids ≥1000mg/L and large changes, and the stability of the effluent water quality cannot be guaranteed. The micro-sand heavy medium rapid sedimentation process has good load compatibility and can stably treat influent suspended solids of SS≤12000mg/L, and has strong water quality adaptability.

(2) Recovery rate of coagulation medium.

The concentration of suspended solids in underground coal mine wastewater is high and fluctuates greatly. The magnetic powder recovery rate of the magnetic separation process will be greatly reduced at a high concentration of SS ≥ 600 mg/L, and the amount of additional micro-sand added will be very large; while the amount of additional micro-sand added in the micro-sand heavy medium rapid sedimentation process is very small, and the sand particles in the incoming water have a suitable specific gravity and can appropriately act as a micro-sand medium, without the need to add micro-sand.

(3) Impact on subsequent deep processing technology.

The concentration of suspended solids in underground coal mine wastewater is high and fluctuates greatly. The magnetic powder recovery rate of the magnetic separation process at high concentration will be greatly reduced, and the PAM dosage will be greatly increased. The lost magnetic powder and excess PAM reagent will enter the water tank with the produced water, making it more difficult to clear the tank; the wear of the lifting pump and piping system is also more obvious; after being lifted to the deep treatment unit on the ground, it will eventually lead to a greatly increased scaling tendency of the subsequent deep treatment membrane (the main reason why many mines are replacing this process), which is not conducive to the normal operation of the subsequent system and the compliance of the produced water with the standard; the leaked magnetic powder may cause the subsequent deep treatment membrane material to be cut.

The amount of micro-sand added in the micro-sand heavy medium rapid sedimentation process is very small, the recovery rate is high, and the amount of PAM added is relatively small, which minimizes the impact on subsequent deep treatment units.

(4) Operating costs.

Compared with magnetic separation, heavy medium rapid sedimentation can save 1/3 of PAC and 3/4 of PAM dosage; heavy medium rapid sedimentation can recover 99% of micro-sand, while the recovery rate of magnetic separation is low and greatly affected by the water quality; the integrated + highly automated design can reduce labor cost investment; the operating cost is lower than that of magnetic separation.

(5) The degree of automation of the process system.

Since the magnetic separation process uses a decentralized unit setting, it is not conducive to the system meeting the automation requirements of unmanned or less-manned operation.

The heavy medium rapid sinking equipment is a skid-mounted equipment, which integrates the processing unit and the automatic control system, has a high degree of automation and is easy to operate.

(6) The process system is simple and requires one-time investment.

The basic treatment route of magnetic separation process is: sedimentation tank + pre-sedimentation adjustment tank + coagulation tank + reaction tank + magnetic separation main machine + magnetic separation drum machine + sludge transfer tank + sludge tank + filter press device;

The basic treatment route of the underground low-carbon treatment process for high-turbidity mine water is: pre-sedimentation adjustment tank + heavy medium rapid sedimentation equipment + sludge tank + filter press device.

It can be seen that the underground low-carbon treatment process of high-turbidity mine water is simple and easy to manage, which greatly reduces the amount of civil engineering and mining construction and reduces one-time investment.

The actual application cases of the underground low-carbon treatment process and system for high-turbidity mine water of the present invention are shown in Table 5 below.

Table 5 Practical application cases

Serial number Mine name Design water volume Setting location 1 Lingxin Coal Mine of Ningxia Coal Industry Company of China National Energy Group 800m ³ /h Downhole 2 Shaanxi Xiaobaodang Mining Co., Ltd. No. 1 Coal Mine 1500m ³ /h Downhole 3 Shaanxi Xiaobaodang Mining Co., Ltd. No. 2 Coal Mine 1500m ³ /h Downhole

According to the feedback from the users, the processing system provided by the present invention is very suitable for the use conditions of coal mines due to its high processing efficiency, small footprint and stable operation;

When the suspended solids in the inlet water fluctuate, it can ensure that the outlet water quality is stable and meets the standards;

The recovery rate of micro-sand added medium is high, and the daily supplement amount is very small, especially when the incoming water contains a lot of sand, there is no need to add more;

The dosage of the drug is small, which can ensure the normal use of the subsequent deep treatment system;

The equipment is highly integrated, no other maintenance work is required, and the labor intensity is low.

The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any person skilled in the art can use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims (10)

1. The process for treating the low carbon in the underground of the high turbidity mine well is characterized by comprising the following steps of:

s1, collecting underground production sewage of a mine into a water collecting tank, feeding the sewage into a coal slime dehydration device through a lifting pump to carry out mud-water separation, conveying the obtained coal slime and separated water to a main conveying belt through a belt, and enabling the separated water to automatically flow into an intermediate water tank;

S2, delivering the separated water of the middle water tank to heavy medium speed submerged treatment equipment, and adding a coagulating agent to obtain clear water and sludge water;

s3, when a goaf is arranged under the coal mine, sludge water in the sludge pond is conveyed to the goaf through a sludge pump, and after natural filtration and interception of the goaf, filtered water flows back to the water collecting pond;

when the goaf is not arranged in the underground coal mine, sludge water in the sludge pond is conveyed to a filter press for filter pressing through a sludge pump, and the filter pressed coal cake is conveyed to a main conveying belt or a mine car for external conveying for coal cake recovery through a belt.

2. The process of claim 1, wherein the coagulating agent comprises polyaluminum chloride and polyacrylamide, wherein the polyaluminum chloride is added at 70-80 mg/L and the polyacrylamide is added at 1.1-1.5 mg/L.

3. The process according to claim 1 or 2, wherein the coagulating agent further comprises a micro-sand having a particle size of 100 to 150 μm and an addition amount of 10g/L, and the raw slime water contains a large amount of particles having a particle size and a specific gravity similar to those of the micro-sand, which can function as micro-sand to some extent, and the addition amount of the micro-sand is appropriately reduced.

4. The system is characterized by comprising a water collecting tank, a raw water lifting pump, a coal slime dewatering device, a middle water tank, a heavy medium lifting pump, a heavy medium speed submerged treatment device, a sludge tank and a sludge lifting pump which are sequentially communicated, wherein the heavy medium speed submerged treatment device is provided with a coagulation tank, an injection tank, a curing tank and a sedimentation tank with a mud scraper which are sequentially adjacent, the height of a partition plate between the coagulation tank and the injection tank is lower than the peripheral height of the coagulation tank, namely, the upper end of the coagulation tank is communicated with the injection tank, the lower end of the partition plate between the injection tank and the curing tank is communicated, the mud scraper is arranged at the upper end of the sedimentation tank, the lower end of the sedimentation tank is connected with a reflux pump, a sand outlet of the sand-water separator is communicated to the upper end of the injection tank through a pipeline, and a mud outlet of the sand-water separator is connected with the sludge tank; stirring paddles are arranged in the coagulation tank, the injection tank and the curing tank, and a clear water outlet is formed in the upper end of the sedimentation tank; the clear water outlet is also connected with a clear water tank, and when a goaf exists in the underground coal mine, a sludge pipe of the sludge lifting pump is communicated to one end of the goaf exists in the underground coal mine, and the other end of the goaf exists in the underground coal mine is communicated to the water collecting tank through the sludge pipe.

5. The system of claim 4, wherein the water collection tank, the intermediate water tank, the recycling water tank and the sludge tank are arranged in a reinforced concrete structure, and wherein the bottom planes of the water collection tank and the intermediate water tank are provided with slopes of 6 degrees to 12 degrees.

6. The system of claim 4, wherein the heavy medium rapid submerged processing equipment is a square skid-mounted carbon steel structure, the raw water lifting pump and the heavy medium lifting pump are dry pumps, and the sludge pump is a slurry pump.

7. The system of claim 4, wherein when the coal mine underground has no production space, the system for treating further comprises a plate-and-frame filter press, the sludge lifting pump is communicated with an inlet of the plate-and-frame filter press through a sludge pipe, and a liquid outlet of the plate-and-frame filter press is communicated with the water collecting tank through a sludge pipe.

8. The system of claim 4, wherein the connecting pipeline between the water collecting tank and the heavy medium lifting pump is a downhole production sewage pipe, and the clear water outlet is connected with the clear water tank by a clear water pipe; the heavy medium rapid submerged treatment equipment, the sludge tank and the sludge lifting pump are connected by adopting sludge pipes.

9. The system of claim 4, wherein an ultrasonic level gauge is arranged at the upper end of the water collecting tank, the middle water tank, the clean water tank and the sludge tank; the two ends of each lifting pump are respectively provided with a manual butterfly valve, flexible joints are respectively arranged between the manual butterfly valves and the lifting pumps, the water outlet end of each lifting pump is also provided with a pressure gauge and a check valve, and a flowmeter is also arranged between the heavy medium lifting pump and the water inlet of the heavy medium rapid submerged processing equipment.

10. The system of any one of claims 4-9, further comprising a PAC dosing device and a PAM dosing device, the PAC dosing device being in communication with the water inlet of the heavy medium rapid sink treatment apparatus, the PAM dosing device being in communication with the upper end of the maturation tank.