Extracting and clarifying tank based on electrostatic conduction liner for electrostatic conduction and interface monitoring

Abstract

The extraction and clarification tank based on the conductive inner lining to realize static electricity leading out and interface monitoring comprises a tank body made of non-metallic material, a continuous conductive inner lining layer laid on the whole inner wall surface of the tank body, a grounding terminal arranged on the outer wall of the tank body and electrically connected with the conductive inner lining layer, an interface meter probe penetrating through the wall of the tank body and extending into the interior and electrically contacting with the conductive inner lining layer, an adjustable weir plate arranged on the tank body and associated with the organic phase outlet or the water phase outlet and used for adjusting the phase interface height in the tank body, and a control system; the interface meter probe is connected with the adjustable weir plate, and according to the phase interface position signal detected by the interface meter probe, the action of the adjustable weir plate is controlled to stabilize the phase interface in a predetermined range, so that the inherent defects of the existing non-metallic material clarification tank can be overcome, and the problems such as safety hidden danger, out-of-control of phase interface monitoring and difficulty in automatic operation in the extraction and separation process can be solved.

Description

Technical Field

[0001] This invention relates to the fields of hydrometallurgy, chemical separation and environmental protection, and in particular to an extraction clarification tank based on a conductive liner to achieve electrostatic discharge and interface monitoring, which is suitable for handling flammable and explosive media. Background Technology

[0002] In the hydrometallurgical and fine chemical separation processes of strategic metals such as lithium, cobalt, and nickel, the mixing and clarification tank is the core unit of continuous extraction operations. The clarification tank's function is to achieve complete separation of the mixed organic and aqueous phases through gravity settling. To cope with the strong corrosiveness of the process media and to reduce equipment weight and manufacturing costs, polypropylene (PP), polyethylene (PE), or fiberglass reinforced plastic (FRP) are commonly used in industry to manufacture clarification tank bodies.

[0003] However, the inherent insulating properties of these non-metallic materials have led to two interconnected and long-standing prominent technical challenges in actual industrial operation: 1. Significant Safety Risks Caused by Static Electricity Accumulation: During the clarification and separation process, the insulating organic phase (such as sulfonated kerosene, 260# solvent oil, etc.) and the continuous aqueous phase generate and accumulate a large amount of static charge due to intense flow, shearing, and collision friction. Since the entire tank is an insulator, an effective charge discharge channel cannot be formed, leading to a continuous increase in electrostatic potential. Experiments and accident cases show that the accumulated static voltage can easily reach thousands or even tens of thousands of volts. Once electrostatic discharge occurs, the generated electric spark is sufficient to ignite flammable organic vapors volatilized within the tank, causing a fire or explosion, seriously threatening life and property safety.

[0004] 2. Failure of Phase Interface Monitoring and Control Functions: A stable phase interface is crucial for ensuring separation efficiency and continuous operation. In industry, radio frequency admittance or capacitive interface meters are widely used for online monitoring. The operating principle of these instruments requires a stable, low-impedance grounding reference point to form a complete measurement loop. When installed on insulated PP / PE tanks, the instruments cannot be reliably grounded, leading to severe signal drift, significantly inaccurate readings, or even complete failure. Operators are forced to rely on manual inspection and experience-based judgment, making precise automated control impossible and increasing the risk of production accidents such as "oil spills" (organic phase loss) or "water spills" (aqueous phase entrainment), resulting not only in economic losses but also increased environmental pressure on subsequent wastewater treatment.

[0005] 3. In existing technologies, although attempts have been made to use local metal grounding rods or external conductive strips, these are all stopgap measures. Local grounding has dead zones and cannot guarantee electrostatic safety for the entire flow field area; external conductive strips are prone to corrosion and detachment, and cannot provide a globally stable equipotential reference surface for the interface meter.

[0006] Our research group's analysis revealed that existing patented technologies primarily focus on optimizing the hybrid structure of clarifiers, leak-proof sealing, or improving the installation of single-function interface meters. No existing patents present a technical solution that simultaneously addresses the issues of static electricity discharge and interface monitoring by installing a continuous conductive lining layer on the inner wall of a non-metallic clarifier and grounding it.

[0007] To address the aforementioned issues, CN121197866A, "A mixing and clarification tank and its liquid level adjustment method, and a radionuclide recovery and extraction system," discloses a method that adjusts the liquid level at the interface between the two phases in the overflow chamber by adjusting the pressure difference between the overflow chamber and the clarification chamber using a pressure regulating component. This avoids increasing the workload of maintenance and repair of the mixing and clarification tank by adding mechanical moving parts. However, it does not address the grounding issues related to static electricity and interface monitoring.

[0008] Therefore, it is of great significance to develop an extraction clarification tank based on a conductive liner to achieve electrostatic discharge and interface monitoring. Summary of the Invention

[0009] The objective of this invention is to overcome the shortcomings of existing methods and provide an extraction clarification tank based on a conductive liner for electrostatic discharge and interface monitoring. This invention overcomes the inherent defects of existing non-metallic clarification tanks and solves the safety hazards caused by the accumulation of static charges generated during extraction and separation due to friction between the two phases, leading to potential combustion and explosion risks. It also addresses the process control problems caused by the tank's insulation, such as unreliable grounding of the online interface meter, loss of phase interface monitoring, and difficulties in automated operation.

[0010] To accomplish the above tasks, the present invention adopts the following technical solution: An extraction clarification tank based on a conductive liner for electrostatic discharge and interface monitoring includes a tank body made of non-metallic material, a continuous conductive liner layer laid on the entire inner wall surface of the tank body, a grounding terminal located on the outer wall of the tank body and electrically connected to the conductive liner layer, an interface meter probe whose sensing element extends through the tank body wall and into the interior and is in electrical contact with the conductive liner layer, an adjustable weir plate located on the tank body and associated with the organic phase outlet or aqueous phase outlet for adjusting the phase interface height within the tank, and a control system. The interface meter probe is connected to the adjustable weir plate and can control the operation of the adjustable weir plate based on the phase interface position signal detected by the interface meter probe, thereby stabilizing the phase interface within a predetermined range.

[0011] The innovation of this invention lies in proposing an integrated solution that constructs a continuous conductive layer on the inner wall of a non-metallic insulating tank and reliably grounds it. This solution is not a simple stacking of components, but rather unifies the two originally contradictory requirements of "static electricity safety discharge" and "instrument measurement reference" through the core element of "conductive lining". At the same time, it eliminates the two inherent defects of non-metallic tanks, resulting in a synergistic safety and control effect of "1+1>2".

[0012] Compared with the prior art, the advantages or effects of the present invention are as follows: (1) Revolutionary improvement in inherent safety: The continuous conductive lining and grounding system provide a global low-resistance discharge path for static charge, which can conduct the generated static electricity to the ground in real time, so that the static potential in the tank is always maintained within a safe range (such as <200V), fundamentally eliminating static electricity explosion accidents, and is particularly suitable for high-risk fields such as petrochemicals and lithium battery material extraction.

[0013] (2) A qualitative leap in measurement and control accuracy: The conductive liner provides a "zero potential" reference surface for the interface meter, which completely solves the signal reference problem and greatly improves the accuracy and stability of interface measurement (measured signal fluctuation <2%). Combined with the adjustable weir plate and DCS system, fully automatic and high-precision closed-loop control of the phase interface can be realized (control accuracy can reach ±5mm), which greatly improves process stability and metal recovery rate.

[0014] (3) Excellent compatibility and economy: This solution retains all the advantages of non-metallic tanks (corrosion resistance, lightweight, and low cost) while eliminating their two major inherent defects through "lining modification". The structure is simple and easy to implement, making it very suitable for upgrading thousands of existing non-metallic clarification tanks to safety and automation. The modification cost is low, the cycle is short, and the benefits are significant.

[0015] (4) Reliable and durable structure: The conductive lining can be made of the most suitable material according to the characteristics of the medium, and is firmly bonded to the tank through bonding, welding and other processes. It is resistant to erosion and corrosion, and its service life is synchronized with that of the tank, requiring almost no additional maintenance. Attached Figure Description

[0016] The specific structure of the invention is shown in the following figures.

[0017] Figure 1 This is a schematic diagram of the cross-sectional structure of an extraction clarification tank based on a conductive liner to achieve electrostatic discharge and interface monitoring, according to the present invention.

[0018] The symbols in the attached diagram represent: 1. Tank body 2. Mixed phase inlet 3. Organic phase outlet 4. Aqueous phase outlet 5. Conductive liner 6. Grounding terminal 7. Interface meter probe 8. Adjustable weir plate 9. Observation port 10. Flow baffle plate The present invention will be further described in detail below with reference to the accompanying drawings. Detailed Implementation

[0019] like Figure 1As shown, according to the present invention, an extraction clarification tank based on a conductive liner for electrostatic discharge and interface monitoring includes a tank body 1 made of non-metallic material, a continuous conductive liner 5 laid on the entire inner wall surface of the tank body 1, a grounding terminal 6 disposed on the outer wall of the tank body 1 and electrically connected to the conductive liner 5, an interface meter probe 7 whose sensing element extends through the wall of the tank body 1 and is in electrical contact with the conductive liner 5, an adjustable weir plate 8 disposed on the tank body 1 and associated with the organic phase outlet 3 or the aqueous phase outlet 4 for adjusting the phase interface height in the tank body 1, and a control system; the interface meter probe 7 is connected to the adjustable weir plate 8 and can control the operation of the adjustable weir plate 8 according to the phase interface position signal detected by the interface meter probe 7, thereby stabilizing the phase interface within a predetermined range.

[0020] The present invention may be further defined as follows: The conductive inner liner 5 is made of any one of conductive rubber, conductive fluoroplastic, corrosion-resistant stainless steel, or titanium Hastelloy metal sheet.

[0021] The resistivity of the conductive inner liner 5 should be less than 10. 4 Ω·cm, with a thickness of 1~5 mm.

[0022] The main body of the tank 1 is made of any one of the following non-metallic materials: polypropylene, polyethylene, or fiberglass, which have excellent corrosion resistance and are lightweight.

[0023] The interface meter probe 7 is either an RF admittance type or a capacitive type.

[0024] The sensing element of the interface meter probe 7 passes through the wall of the tank 1 and extends into its interior. The installation of the sensing element or probe is in electrical contact with the conductive inner lining layer 5, which can measure the phase interface position signal in the clarification tank in real time, thereby obtaining a stable measurement grounding reference.

[0025] The metal housing or its fixing component of the interface meter probe 7 forms a low-resistance electrical connection with the conductive inner lining layer 5 laid on the inner wall of the tank 1, so that the measurement circuit of the interface meter probe 7 can use the conductive inner lining layer as a reference ground.

[0026] The fixing component is a mounting flange, which forms an electrical contact with the conductive inner liner 5 by pressing a conductive sealing gasket together.

[0027] The control system includes a programmable logic controller (PLC) and a human-machine interface (HMI).

[0028] The programmable logic controller (PLC) receives the deviation signal from the interface meter probe 7 and outputs control commands to drive the actuator connected to the adjustable weir plate 8 to rise and fall, thereby changing the height of the organic phase overflow port and thus precisely adjusting the phase interface position in the tank 1. Example

[0029] Application of conductive rubber-lined clarification tank in cobalt extraction Tank 1: Made of PPH (homogeneous polypropylene) sheet welded together, with dimensions of length × width × height = 4m × 1.5m × 2m.

[0030] Conductive inner lining layer 5: Made of 2mm thick conductive nitrile rubber sheet with a volume resistivity ≤5×10³ Ω·cm. It is fully coated on the inner wall of the tank using acid-resistant conductive adhesive and secured with plastic anchor bolts to ensure a continuous and seamless lining.

[0031] Grounding system: Multiple copper grounding connection points are reserved on the lining. After being connected in parallel with 25mm² copper braided tape, they are led to the stainless steel grounding terminal 6 on the outer wall of the tank. The overall grounding resistance is tested to be <4Ω.

[0032] Interface monitoring: Install the radio frequency admittance interface meter probe 7, whose stainless steel flange is tightly pressed against the conductive inner liner 5 through a conductive sealing gasket.

[0033] Automatic control: An adjustable weir plate 8 driven by a motor is set at the organic phase outlet 3, and the signal from the interface meter probe 7 is connected to the PLC to form a PID control loop.

[0034] Results: In a comparative test conducted in a cobalt ore extraction workshop (processing capacity 50 m³ / h), the electrostatic potential of the tank after the modification decreased from ≥8000V to <100V; the interface meter signal was stable, achieving automatic control with an accuracy of ±10mm, reducing organic phase loss by approximately 15 tons per year, demonstrating significant safety and economic benefits.

[0035] Comparative Example 1 Traditional PP settling tank A pure PP material clarifying tank of the same size as in Example 1 was used, without any conductive lining or dedicated grounding measures. Under the same operating conditions, the electrostatic potentiometer showed a potential that was consistently higher than 5000V; the installed RF admittance interface meter had high signal noise (fluctuation >20%), making it unsuitable for automatic control and requiring manual inspection and adjustment of the outlet valve every 2 hours.

[0036] Experimental Data Comparison Table The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. For example, the conductive inner liner can be made of other conductive composite materials; the grounding method can be multi-point grounding; the interface gauge type can be selected according to process requirements; the control method can be linked with the feed pump, valves, etc., all of which fall within the scope defined by the claims of the present invention.

Claims

1. An extraction clarification tank based on a conductive liner for electrostatic discharge and interface monitoring, comprising a tank body (1) made of non-metallic material, characterized in that... It also includes a continuous conductive inner lining layer (5) laid on the entire inner wall surface of the tank (1), a grounding terminal (6) provided on the outer wall of the tank (1) and electrically connected to the conductive inner lining layer (5), an interface meter probe (7) with a sensing element extending through the wall of the tank (1) and in electrical contact with the conductive inner lining layer (5), an adjustable weir plate (8) associated with the organic phase outlet (3) or the aqueous phase outlet (4) on the tank (1) and used to adjust the phase interface height in the tank (1), and a control system; the interface meter probe (7) is connected to the adjustable weir plate (8) and can control the adjustable weir plate (8) to move according to the phase interface position signal detected by the interface meter probe (7) to stabilize the phase interface within a predetermined range.

2. The extraction clarification tank according to claim 1, characterized in that: The conductive inner liner (5) is made of any one of conductive rubber, conductive fluoroplastic, corrosion-resistant stainless steel, or titanium Hastelloy metal sheet.

3. The extraction clarification tank according to claim 1 or 2, characterized in that: The resistivity of the conductive inner liner (5) should be less than 10. 4 Ω·cm, with a thickness of 1~5 mm.

4. The extraction clarification tank according to claim 1, characterized in that... The main body of the tank (1) is made of any one of the non-metallic materials, such as polypropylene, polyethylene or fiberglass, which have excellent corrosion resistance and are lightweight.

5. The extraction clarification tank according to claim 1, characterized in that... The interface meter probe (7) is either radio frequency admittance type or capacitive type.

6. The extraction clarification tank according to claim 1 or 5, characterized in that: The sensing element of the interface meter probe (7) passes through the wall of the tank (1) and extends into its interior. The installation of the sensing element or probe is in electrical contact with the conductive inner liner (5), which can measure the phase interface position signal in the clarifying tank in real time, thereby obtaining a stable measurement grounding reference.

7. The extraction clarification tank according to claim 1, characterized in that: The metal housing or its fixing component of the interface meter probe (7) forms a low-resistance electrical connection with the conductive inner lining (5) laid on the inner wall of the tank (1), so that the measurement circuit of the interface meter probe (7) can use the conductive inner lining as a reference ground.

8. The extraction clarification tank according to claim 7, characterized in that... The fixing component is a mounting flange, which forms an electrical contact with the conductive inner liner (5) by pressing a conductive sealing gasket together.

9. The extraction clarification tank according to claim 1, characterized in that... The control system includes a programmable logic controller (PLC) and a human-machine interface (HMI).

10. The extraction clarification tank according to claim 1 or 9, characterized in that... The programmable logic controller (PLC) receives the deviation signal from the interface meter probe (7) and outputs control commands to drive the actuator connected to the adjustable weir plate (8) to rise and fall, thereby changing the height of the organic phase overflow port and thus precisely adjusting the phase interface position in the tank (1).

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