Hollow fiber membrane pyrogenic process lithium resource recovery and pollution treatment system

Abstract

The utility model discloses a hollow fiber membrane pyrogenic process lithium resource recovery and pollution treatment system. The method is characterized in that lithium chloride is accurately intercepted and recovered by using a hollow fiber membrane as a recovery stage of a filter material; the pollutants in the flue gas are subjected to catalytic oxidation by a removal stage of a hollow fiber membrane loaded catalyst; the adsorption stage of the hollow fiber membrane loaded adsorbent is used for absorbing difficult-to-oxidize substances; sulfur, nitric oxide and hydrogen chloride are absorbed by a spray tower. The system formed by the four links overcomes the defects of wet recovery, and is efficient, energy-saving and emission-reducing.

Description

Technical Field

[0001] Hollow fiber membrane pyrometallurgical lithium resource recovery and pollution treatment system. Including lithium smelting and lithium resource regeneration fields. Background Art

[0002] There are two types of lithium resource acquisition and recovery technologies: wet method and pyrometallurgical method. Since wet smelting requires a large amount of acid and extraction liquid, the process is complex, the cost is high, and too many secondary pollutants are generated, and the treatment cost is extremely high.

[0003] A new process route for obtaining and recovering lithium resources by pyrometallurgy is to add CI in a high-temperature furnace to convert the lithium in the slag into easily volatile LiCI, thereby achieving the goal of efficiently obtaining lithium resources from the smoke. The main problem faced by pyrometallurgy recovery is the low recovery rate. Since lithium resources are extremely valuable, too much material escapes through the smoke and is difficult to accept.

[0004] To realize this design, the core difficulty lies in how to completely intercept the lithium in the flue gas. This requires the filter material to have an interception efficiency of more than 99.9%, an interception accuracy of micrograms, resistance to hydrogen chloride corrosion, and high temperature. At the same time, it is also necessary to deal with complex pollutants such as nitrogen oxides, sulfur oxides, hydrogen fluoride, VOCs, and dioxins generated by pyrometallurgy. This is a difficult problem that cannot be solved by current traditional technologies. Utility Model Content

[0005] ]To this end, the purpose of the present invention is to provide a system solution that can meet the above requirements.

[0006] A hollow fiber membrane pyrometallurgical lithium resource recovery and pollution treatment system is composed of a smoke hood (01), a heat exchanger (02), a recovery stage (03), a catalyst chamber (04), an ozone generator (05), a mixer (06), a small spray tower (07), a catalyst recovery tower (08), a removal stage (09), an adsorbent chamber (010), an adsorption stage (011), and a large spray tower (012). The system is characterized in that the filter material used is a membrane assembly composed of hollow fiber membrane filaments, and the membrane assembly is used to form a hollow fiber membrane array; the recovery stage (03) is equipped with a hollow fiber membrane array, and its air outlet is connected to the mixer (06); the ozone output pipe of the ozone generator (05) is connected to the mixer (06); the catalyst bin (04) is connected to the mixer (06) through a valve; the air outlet of the small spray tower (07) is connected to the mixer (06); the air outlet of the mixer (06) is connected to the removal stage (09); the removal stage (09) is equipped with a hollow fiber membrane array, and the powder in the lower chamber of the removal stage (09) is removed. The catalyst is attracted by the negative pressure and covers the surface of the membrane filaments to form a replaceable catalyst bed; the air outlet of the removal stage (09) is connected to the air inlet of the adsorption stage (011); the air inlet of the adsorption stage (011) is connected to the adsorbent bin (010) through a valve; the chamber of the adsorption stage (011) is equipped with a hollow fiber membrane array, and the adsorbent entering from the adsorbent bin (010) is attracted by the negative pressure to form a replaceable adsorption bed on the surface of the membrane filaments; the air outlet of the adsorption stage (011) is connected to the large spray tower (012), and the large spray tower (012) is connected to the large spray tower (012). The air outlet of the tower (012) is connected to the fan and the chimney; the bottom of the removal stage (09) bin is connected to the feed inlet of the catalyst recovery tower (08) through a powder passage, and the discharge port of the catalyst recovery tower (08) is connected to the mixer (06) through a powder passage; the powder passage is a screw feeder or an air flow feeder; the exhaust port of the catalyst recovery tower (08) is connected to the air inlet of the small spray tower (07) through an air pipe; and the air outlet of the small spray tower (07) is connected to the mixer (06) through an air pipe.

[0007] The flue gas emitted from the furnace passes through the heat exchanger (02) to reduce its temperature to below 200 degrees, and its heat energy is recovered. After the flue gas enters the recovery stage (03), the various particulate matter and lithium chloride dust contained in it are intercepted by the hollow fiber membrane in the recovery stage (03). Due to the extremely high interception accuracy of the membrane, most of the lithium resources are attached to the surface of the membrane and fall to the bottom of the bin through backblowing. The bottom cover is opened to collect the mixture of collected materials and particulate matter into the barrel.

[0008] The flue gas with dust removed enters the mixer (06). At the same time, ozone from the ozone generator (05) and the catalyst from the catalyst chamber (04) also enter the mixer (06), and the three are mixed to produce a catalytic oxidation reaction. Further, part of the powdered catalyst is suspended in the chamber of the removal stage (09), and part of the catalyst is adsorbed onto the surface of the hollow fiber membrane in the chamber of the removal stage (09), forming a catalytic bed of replaceable catalysts. Under the action of catalytic oxidation, sulfur and nitrogen oxides are converted into water-soluble valence states and are absorbed in the large spray tower (012) at the back together with the hydrogen chloride in the flue gas. VOCs in the flue gas are also oxidized and degraded.

[0009] During the oxidation and degradation of VOCs, many intermediates are formed, such as acetic acid and benzoic acid. These intermediates are difficult to oxidize and will adhere to the catalyst surface, causing the catalyst to fail. In response to this, backflush is started to blow the spent catalyst off the membrane wire, and new catalyst is sprayed in again to form a new layer of catalyst bed. The spent catalyst that falls to the bottom of the removal stage (09) is sent to the catalyst recovery tower (08) through the powder passage, and the intermediates are volatilized by heating to achieve desorption recovery. The recovered catalyst returns to the removal bin (09) through the mixer (06) again.

[0010] The intermediate gas removed from the catalyst recovery tower (08) enters the small spray tower (07). The water temperature of the small spray tower is above (65) degrees, which can absorb VOC substances that are difficult to oxidize. The incompletely degraded tail gas returns to the removal chamber (09) through the mixer (06) and is oxidized again.

[0011] The flue gas from the large spray tower (012) enters the adsorption stage (011). The adsorbent bin (010) stores adsorbents such as alumina powder, activated carbon, molecular sieve, and activated coke. The adsorbent is sprayed into the adsorption stage (011) chamber to form a suspended state. Part of the adsorbent is attracted by the negative pressure and adheres to the surface of the membrane to form an adsorption bed. The chlorides and other difficult-to-oxidize substances are adsorbed by the adsorbent. When the adsorbent is close to saturation, backflush is started to blow it off, and new adsorbent is sprayed in. A new layer of adsorption bed is formed again, and this cycle repeats. The spent adsorbent is discharged from the bin. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Attached Figure 1 This is a schematic diagram of an example of a hollow fiber membrane pyrometallurgical lithium resource recovery and pollution treatment system. DETAILED DESCRIPTION

[0013] The supporting point of the feasibility of the utility model is that the hollow fiber membrane used truly possesses the performance required for pyrometallurgical lithium resource recovery and pollution treatment, and is not just a design and prediction.

[0014] The inventor and the applicant have specially developed a hollow fiber membrane for heavy pollution air purification, which has a pore size of 0.1--40um, slender holes, and an average pore size of about 2um, which is much smaller than the 22---60um of the bag filter and is equivalent to a 13-level high efficiency filter (HEPA). Therefore, it has the properties of HEPA and can have a high filtration efficiency; since it does not require the help of powder cakes, it can directly achieve the ideal filtration efficiency, avoiding the wind resistance caused by the manufacture of powder cakes. Since the inherent pore diameter wind resistance is equivalent to the powder cake wind resistance, it can achieve a wind resistance similar to that of the bag; since polytetrafluoroethylene material is used, the thickness reaches 0.5mm, it has the characteristics of water and oil repellency, acid and alkali resistance, anti-aging, smooth surface, and avoids friction, so it has a long service life; since the diameter of the hollow fiber membrane is much smaller than that of the bag, the specific surface area is large, so under the same volume or material weight conditions, the ventilation volume is easier to increase; due to the large specific surface area, the materials used are greatly reduced, the manufacturing cost is reduced accordingly, and a lower cost can be achieved.

[0015] The "Trace-Level Filtration Materials and Equipment for Heavy Pollution Flue Gases" with this hollow fiber membrane as the theme has been included in the "Catalogue of Major Environmental Protection Equipment Encouraged for Development by the State 2023".

[0016] A "Trace Level Lead Fume Treatment Demonstration Project" was implemented in Shaoguan, Guangdong. A test report issued by the South China Institute of Environmental Technology of the Ministry of Ecology and Environment showed that in the continuous casting and rolling section, the upstream import of lead and its compounds was 17.9-65.7 mg / m³, and the downstream export was 0.3-4.3 ug / m³, the upstream import of particulate matter was 13.8-123 mg / m³, and it was not detected at the downstream export (the detection limit was 0.5 mg / m³), with an average efficiency of 99.97%; in the grinding section, the upstream import of lead and its compounds was 87.6-333 ug / m³, and it was not detected at the downstream export---0.3 ug / m³ (the detection limit was 0.2 ug / m³), the upstream import of particulate matter was 1.1-11.1 mg / m³, and it was not detected at the downstream export (the detection limit was 0.5 mg / m'), with an average filtration accuracy of 0.2 ug / m³.

[0017] Due to the similar melting points, it is expected that the hollow fiber membrane specially developed for heavy pollution air purification will have the same effect on intercepting lithium aerosols as it does on intercepting lead aerosols.

Claims

1. A hollow fiber membrane pyrometallurgical lithium resource recovery and pollution treatment system, comprising a fume hood (01), a heat exchanger (02), a recovery stage (03), a catalyst chamber (04), an ozone generator (05), a mixer (06), a small spray tower (07), a catalyst recovery tower (08), a removal stage (09), an adsorbent chamber (010), an adsorption stage (011), and a large spray tower (012), characterized in that The filter material used is a membrane assembly composed of hollow fiber membrane filaments, and the membrane assembly is used to form a hollow fiber membrane array; the recovery stage (03) is equipped with a hollow fiber membrane array, and its air outlet is connected to the mixer (06); the ozone output pipe of the ozone generator (05) is connected to the mixer (06); the catalyst bin (04) is connected to the mixer (06) through a valve; the air outlet of the small spray tower (07) is connected to the mixer (06); the air outlet of the mixer (06) is connected to the removal stage (09); the removal stage (09) is equipped with a hollow fiber membrane array, and the powdered catalyst entering the lower chamber of the removal stage (09) is attracted by negative pressure and covers the surface of the membrane filaments to form a replaceable catalyst bed; the air outlet of the removal stage (09) is connected to the air inlet of the adsorption stage (011); the air inlet of the adsorption stage (011) is connected to the air outlet of the adsorption stage (011); The valve is connected to the adsorbent bin (010); a hollow fiber membrane array is installed in the bin of the adsorption stage (011); the adsorbent entering from the adsorbent bin (010) is attracted by negative pressure to form a replaceable adsorption bed on the surface of the membrane fibers; the air outlet of the adsorption stage (011) is connected to the large spray tower (012); the air outlet of the large spray tower (012) is connected to the fan and the chimney; the bottom of the removal stage (09) bin is connected to the feed inlet of the catalyst recovery tower (08) through a powder passage; the discharge port of the catalyst recovery tower (08) is connected to the mixer (06) through a powder passage; the powder passage is a spiral feeder or an air flow feeder; the exhaust port of the catalyst recovery tower (08) is connected to the air inlet of the small spray tower (07) through an air pipe; the air outlet of the small spray tower (07) is connected to the mixer (06) through an air pipe.

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