Method for reducing magnetic foreign matters by tubular vibration feeding conveyor for producing lithium hydroxide monohydrate

Abstract

The invention discloses a method for reducing magnetic foreign matters by a tubular vibratory feeding conveyor for producing lithium hydroxide monohydrate, and aims to solve the problems of deliquescence dust pollution, material adhesion and blockage and the like caused by easy introduction of magnetic foreign matters, insufficient sealing and the like of existing lithium hydroxide monohydrate conveying equipment. By constructing a totally-closed conveying system of a de-ironing separator surge bin, an electromagnetic de-ironing separator, a tubular vibrating feeding conveyor and a small packing machine bin and combining with an ultra-high molecular weight polyethylene lining arranged in a key component, the problems of deliquescence, carbonization, pollution and the like of lithium hydroxide monohydrate are effectively solved, the harsh requirements of battery-grade (the purity is greater than or equal to 99.5%) products are met, and the product quality is improved. Meanwhile, magnetic foreign matter control and conveying stability are achieved.

Description

Technical Field

[0001] This invention relates to a method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor used in the production of lithium hydroxide monohydrate. Background Technology

[0002] Lithium hydroxide monohydrate is a key basic lithium salt in the production of cathode materials for lithium-ion batteries such as lithium iron phosphate and lithium cobalt oxide. The product is in the form of fine white crystals or powder and has the following significant characteristics: high hygroscopicity (prone to deliquescence), rapidly absorbing moisture and clumping when exposed to air, affecting product quality; strong corrosiveness, corroding most metal materials, requiring high-quality equipment; and significant adhesion, as the fine particles easily adhere to equipment surfaces, causing problems such as poor transport, blockages, residues, and cross-contamination. High purity is required; battery-grade products have extremely strict requirements for controlling the content of metal impurities, and metal contamination introduced by equipment wear must be strictly avoided during transport.

[0003] Currently, in the short-distance conveying process of lithium hydroxide monohydrate after demagnetization and into packaging, screw conveyors, chutes, or ordinary tubular conveyors are commonly used, but these devices all have inherent drawbacks: Screw conveyors: The screw blades and pipe walls can easily squeeze and grind the materials, producing metal powder pollution, introducing magnetic foreign objects, affecting product quality, and causing economic losses.

[0004] Sluice box: It has a semi-completely open structure. The friction between the material and the metal introduces magnetic foreign objects, and it cannot isolate the air, which will lead to the deliquescence of the material and the carbonization of lithium hydroxide. At the same time, there are sealing and cleaning problems, which can easily generate dust and pollute the environment.

[0005] Ordinary tubular conveyors: Although they have good sealing performance, they lack effective anti-friction design. Materials can easily carry in metal foreign objects after rubbing against the pipe wall, which will eventually lead to excessive magnetic foreign objects in the product. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for reducing magnetic foreign objects in a tubular vibrating feeder for producing lithium hydroxide monohydrate, in view of the shortcomings of the prior art.

[0007] The technical solution of this invention to solve the above technical problems is: a method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor for producing lithium hydroxide monohydrate, characterized by comprising the following steps: The lithium hydroxide monohydrate from the front end is sequentially fed into the iron separator buffer chamber, the electromagnetic iron separator for demagnetization, the tubular vibrating feeder conveyor, and the small hopper of the packaging machine for packaging. The various devices are seamlessly connected through sealed connectors to form a completely closed production process system. The lithium hydroxide monohydrate material enters the iron separator buffer chamber for buffering. The iron separator buffer chamber adopts a conical structure with an effective volume of 1.5m³, a cone angle of 30°, and is made of SS304 stainless steel. Its inner wall is lined with ultra-high molecular weight polyethylene with a thickness of 1.00mm. A star-shaped discharge valve is installed at the bottom of the magnetic separator buffer chamber, and uniform feeding is achieved through quantitative control of the star-shaped discharge valve. The material continuously enters the electromagnetic separator for deep demagnetization treatment; and the cavity and components in contact with the material are all made of SS304 stainless steel. After demagnetization, lithium hydroxide monohydrate material is conveyed to the small hopper of the packaging machine via a tubular vibrating feeder. The part of the tubular vibrating feeder that comes into contact with the material is lined with ultra-high molecular weight polyethylene with a thickness of 1.00 mm, while the exposed part is made of SS304 stainless steel. Meanwhile, the small hopper of the packaging machine adopts a conical structure with an effective volume of 0.8 m³ and a cone angle of 30°. It is made of SS304 stainless steel, and its inner wall is lined with an ultra-high molecular weight polyethylene with a thickness of 1.00 mm.

[0008] The present invention further specifies the following: Preferably, the ultra-high molecular weight polyethylene lining of the iron remover buffer chamber and the small material hopper of the packaging machine is a detachable structure, and the splicing of the lining adopts a seamless connection process with a splicing gap of ≤0.1mm.

[0009] Preferably, a sealing gasket is provided at the connection between the iron separator buffer chamber and the rotary valve, and the inner wall of the rotary valve cavity is coated with ultra-high molecular weight polyethylene with a coating thickness ≥0.8mm.

[0010] Preferably, the electromagnetic separator has a background field strength peak of ≥5000Gs under hot working conditions, a field strength peak of ≥20000Gs at the working point, a magnetic field coverage area length of ≥1.2m, and a material residence time within the magnetic field area of ​​≥3s.

[0011] Preferably, the ultra-high molecular weight polyethylene liner of the tubular vibrating feeder is an integral structure that covers the entire material contact area of ​​the inner wall of the conveying pipe, and its surface roughness Ra≤0.8μm.

[0012] Preferably, the ultra-high molecular weight polyethylene liner has a molecular weight ≥ 3 million, a Rockwell hardness D ≥ 60, and an elongation at break ≥ 300%.

[0013] Beneficial effects: This invention seamlessly connects various devices through sealed connectors to form a completely closed production process system, isolating air throughout the process and completely solving the problems of easy moisture absorption, clumping, and carbonization of lithium hydroxide monohydrate; and the dust emission concentration during dynamic conveying is ≤10mg / m³, which not only avoids material loss but also eliminates dust pollution in the environment, while solving the problems of deliquescence, carbonization, and dust pollution caused by the open structure of the chute. The present invention uses a removable ultra-high molecular weight polyethylene liner inside the iron separator buffer chamber and the small material hopper of the packaging machine. This further reduces direct contact between materials and metal, reduces frictional corrosion between materials and the metal inside the hopper, and further reduces the introduction of magnetic foreign objects. At the same time, the liner adopts a removable seamless splicing structure with splicing gaps ≤0.1mm, which facilitates cleaning and replacement and further reduces maintenance difficulty. The part of the tubular vibrating feeder that contacts the material adopts an integral ultra-high molecular weight polyethylene liner, covering the entire material contact area of ​​the inner wall of the conveying pipe. Its surface roughness Ra≤0.8μm has an extremely low coefficient of friction and surface energy, is wear-resistant, corrosion-resistant, and self-lubricating. It can effectively prevent the adhesion of lithium hydroxide materials and the entry of powder generated by friction between materials and metal, and reduce magnetic foreign objects. The ultra-high molecular weight polyethylene lining has a molecular weight ≥3 million, Rockwell hardness D≥60, and elongation at break ≥300%. It has excellent wear resistance and resistance to lithium hydroxide monohydrate corrosion, which can reduce the wear and corrosion of materials on the equipment. Compared with traditional metal contact conveying equipment, it can significantly extend the service life of the equipment and reduce the maintenance cost of the equipment. This invention employs a dual protection system: a final electromagnetic separator for deep demagnetization and a full-process ultra-high molecular weight polyethylene liner for isolation. The electromagnetic separator boasts a peak field strength of ≥20000Gs at its hot operating point, a magnetic field coverage length of ≥1.2m, and a material residence time of ≥3s, effectively intercepting magnetic foreign matter generated at the front end. Simultaneously, it avoids direct contact between the material and metal materials throughout the process, eliminating metal powder contamination caused by friction and compression. Ultimately, the content of magnetic foreign matter in the material is ≤5ppm, meeting the stringent purity requirements of battery-grade lithium hydroxide monohydrate (purity ≥99.5%). Detailed Implementation Example 1

[0014] This embodiment provides a method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor used in the production of lithium hydroxide monohydrate, characterized by the following steps: The lithium hydroxide monohydrate from the front end is sequentially fed into the iron separator buffer chamber, the electromagnetic iron separator for demagnetization, the tubular vibrating feeder conveyor, and the small hopper of the packaging machine for packaging. The various devices are seamlessly connected through sealed connectors to form a completely closed production process system. The lithium hydroxide monohydrate material enters the iron separator buffer chamber for buffering. The iron separator buffer chamber adopts a conical structure with an effective volume of 1.5m³, a cone angle of 30°, and is made of SS304 stainless steel. Its inner wall is lined with ultra-high molecular weight polyethylene with a thickness of 1.00mm. A star-shaped discharge valve is installed at the bottom of the magnetic separator buffer chamber, and uniform feeding is achieved through quantitative control of the star-shaped discharge valve. The material continuously enters the electromagnetic separator for deep demagnetization treatment; and the cavity and components in contact with the material are all made of SS304 stainless steel. After demagnetization, lithium hydroxide monohydrate material is conveyed to the small hopper of the packaging machine via a tubular vibrating feeder. The part of the tubular vibrating feeder that comes into contact with the material is lined with ultra-high molecular weight polyethylene with a thickness of 1.00 mm, while the exposed part is made of SS304 stainless steel. Meanwhile, the small hopper of the packaging machine adopts a conical structure with an effective volume of 0.8 m³ and a cone angle of 30°. It is made of SS304 stainless steel, and its inner wall is lined with an ultra-high molecular weight polyethylene with a thickness of 1.00 mm.

[0015] The ultra-high molecular weight polyethylene (UHMWPE) linings of the aforementioned iron separator buffer chamber and packaging machine small hopper are detachable structures, with seamless joints and gaps ≤0.1mm. Sealing gaskets are installed at the connection between the iron separator buffer chamber and the rotary valve, and the inner wall of the rotary valve cavity is coated with an UHMWPE layer with a thickness ≥0.8mm. Under hot conditions, the electromagnetic iron separator has a background field strength peak ≥5000Gs, a working point field strength peak ≥20000Gs, a magnetic field coverage area length ≥1.2m, and a material residence time ≥3s within the magnetic field area. The UHMWPE lining of the tubular vibrating feeder is an integral structure, covering the entire material contact area of ​​the conveying pipe, with a surface roughness Ra ≤0.8μm. The UHMWPE lining has a molecular weight ≥3 million, Rockwell hardness D ≥60, and elongation at break ≥300%.

[0016] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor used in the production of lithium hydroxide monohydrate, characterized in that, Specifically, the following steps are included: The lithium hydroxide monohydrate from the front end is sequentially fed into the iron separator buffer chamber, the electromagnetic iron separator for demagnetization, the tubular vibrating feeder conveyor, and the small hopper of the packaging machine for packaging. The various devices are seamlessly connected through sealed connectors to form a completely closed production process system. The lithium hydroxide monohydrate material enters the iron separator buffer chamber for buffering. The iron separator buffer chamber adopts a conical structure with an effective volume of 1.5m³, a cone angle of 30°, and is made of SS304 stainless steel. Its inner wall is lined with ultra-high molecular weight polyethylene with a thickness of 1.00mm. A star-shaped discharge valve is installed at the bottom of the magnetic separator buffer chamber, and uniform feeding is achieved through quantitative control of the star-shaped discharge valve. The material continuously enters the electromagnetic separator for deep demagnetization treatment; and the cavity and components in contact with the material are all made of SS304 stainless steel. After demagnetization, lithium hydroxide monohydrate material is conveyed to the small hopper of the packaging machine via a tubular vibrating feeder. The part of the tubular vibrating feeder that comes into contact with the material is lined with ultra-high molecular weight polyethylene with a thickness of 1.00 mm, while the exposed part is made of SS304 stainless steel. Meanwhile, the small hopper of the packaging machine adopts a conical structure with an effective volume of 0.8 m³ and a cone angle of 30°. It is made of SS304 stainless steel, and its inner wall is lined with an ultra-high molecular weight polyethylene with a thickness of 1.00 mm.

2. The method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor for producing lithium hydroxide monohydrate according to claim 1, characterized in that: The ultra-high molecular weight polyethylene lining of the iron separator buffer chamber and the small material hopper of the packaging machine is a detachable structure, and the splicing of the lining adopts a seamless connection process with a splicing gap of ≤0.1mm.

3. The method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor for producing lithium hydroxide monohydrate according to claim 1, characterized in that: The connection between the iron separator buffer chamber and the rotary valve is equipped with a sealing gasket, and the inner wall of the rotary valve cavity is coated with ultra-high molecular weight polyethylene with a coating thickness ≥0.8mm.

4. The method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor for producing lithium hydroxide monohydrate according to claim 1, characterized in that: The electromagnetic separator has a background field strength peak of ≥5000Gs under hot working conditions, a working field strength peak of ≥20000Gs, a magnetic field coverage area length of ≥1.2m, and a material residence time within the magnetic field area of ​​≥3s.

5. The method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor for producing lithium hydroxide monohydrate according to claim 1, characterized in that: The ultra-high molecular weight polyethylene liner of the tubular vibrating feeder is an integral structure that covers the entire material contact area of ​​the inner wall of the conveying pipe, and its surface roughness Ra≤0.8μm.

6. The method for reducing magnetic foreign objects in a tubular vibrating feeder conveyor for producing lithium hydroxide monohydrate according to claim 1, characterized in that: The ultra-high molecular weight polyethylene liner has a molecular weight ≥3 million, a Rockwell hardness D ≥60, and an elongation at break ≥300%.