WO2007129845A1

WO2007129845A1 - Apparatus and method for recycling of used zinc-carbon and alkaline batteries

Info

Publication number: WO2007129845A1
Application number: PCT/KR2007/002218
Authority: WO
Inventors: Shun Myung Shin; Jeong Soo Sohn; Dong Hyo Yang; Tae Hyun Kim; Jin Gu Kang; Kyung Bae Kim
Original assignee: Korea Institute Of Geoscience & Mineral Resources
Priority date: 2006-05-04
Filing date: 2007-05-04
Publication date: 2007-11-15
Also published as: KR100709268B1

Abstract

The present invention relates to an apparatus and method for recovering valuable metals from spent batteries. An object of the present invention is to provide an apparatus and method for recycling spent zinc-carbon batteries and alkaline batteries, which can reduce transportation cost by treating spent batteries through physical and chemical processes in one place with a batch treatment and efficiently recover valuable metals using an eddy current separator, a dust collector and a cooler without generating pollutants. The apparatus comprises: a dust collection means for sucking dust generated in crushed spent batteries; a magnetic separation means for separating magnetic materials from the crushed spent batteries; a size separation means for sorting nonmagnetic materials in the crushed spent batteries according to size; an eddy current separation means for separating zinc and carbon rods from the nonmagnetic materials larger than a given size, passed through the size separation means; and a recovering means for recovering valuable metals from the nonmagnetic materials smaller than a given size, passed through the size separation means. The method comprises: sucking dust generated in spent batteries; separating magnetic materials from the crushed spent batteries; sorting nonmagnetic materials in the crushed spent batteries according to size; separating zinc and carbon rods from the nonmagnetic materials larger than a given size using an eddy current; forming powder by drying the nonmagnetic materials smaller than a given size in an electric furnace; and leaching zinc by adding the powder to an alkaline leaching solution.

Description

APPARATUS AND METHOD FOR RECYCLING OF USED ZINC-CARBON AND ALKALINE BATTERIES

Technical Field

[1] The present invention relates to an apparatus and method for recycling spent batteries, and more particularly to an apparatus and method, which can recover valuable metals from spent zinc-carbon batteries and alkaline batteries, using an eddy current separator and a dust collector without discharging pollutants.

[2]

Background Art

[3] Batteries generally include, as electrode materials, variable metals, such as nickel, manganese, lithium, cadmium, mercury, silver and cobalt, depending on the type and manufacturer thereof.

[4] In Korea lacking natural resources, valuable metals contained in spent batteries are important as new secondary resources, and hazardous substances contained in used batteries cause environmental pollution. The spent batteries, therefore, should be recycled rather than open dumping, in order to recover valuable metals and make the spent batteries harmless.

[5] Battery wastes after being used for a given period of time came from primary batteries, such as zinc-carbon batteries, alkaline batteries, lithium primary batteries, silver oxide batteries and mercury batteries, and secondary batteries, such as nickel- cadmium batteries and lithium ion batteries.

[6] Among them, zinc-carbon batteries and alkaline batteries, which are the majority of spent batteries, contain manganese, zinc, iron, nickel, etc., and are used annually in an amount of more than about 15,000 tons corresponding to about one billion batteries.

[7] In the case of silver oxide batteries that are used power sources for watches, about

60,000 tons of spent batteries are annually collected.

[8] In spent batteries, zinc and manganese are contained in an amount of 20%, respectively, and iron in an amount of 15%. When these metals are recovered and recycled, it is expected to reduce the importation of manganese, of which the supply entirely depends on importation, and zinc having a domestic self-sufficiency rate of 2.7%. Also, the recycling of spent batteries makes it possible to prevent environmental pollution and reduce the generation of waste.

[9] In the case of foreign countries, technology for recycling spent zinc-carbon batteries and spent alkaline/zinc-carbon batteries, which has been developed up to date, aim mainly to separate and recover hazardous heavy metal mercury. [10] In Itomuka Mine constructed in Hokkaido, Japan, by Japan Clean Center, a reprocessing facility having an annual capacity of 6000 tons is operated. In this facility, mercury is recovered using a conventional high-temperature thermal treatment technology, and spent manganese is supplied as a raw material. However, there has a drawback in economic terms that the price of products is low compared to transportation cost.

[11] Chemtec GmbH, Austria, also recycles spent zinc-carbon batteries and alkaline/ zinc-carbon batteries through a dry process and employs a thermal waste treatment process having an annual treatment capacity of 8,000 tons.

[12] The thermal waste treatment process is a process in which spent batteries are thermally treated at a temperature of 700 ⁰C, and then separated into magnetic materials and non-magnetic materials through physical crushing and screening processes. Iron scrap is treated through this process in iron mills, and fine powder (32% zinc, 27% manganese and 9% iron) is treated in zinc oxide recycling firms.

[13] Recymet GmbH, Swiss, recycles spent batteries as well using a dry process in a manner similar to that of Chemtec GmbH.

[14] The above-described processes, however, have a problem in that, among nonmagnetic materials contained in treated spent batteries, zinc usable as a semi-finished product is not sufficiently separated from a carbon rod.

[15] For this reason, there are problems in that the volume of crushed spent batteries increases and the recovery of valuable metals is reduced due to subsequent chemical treatment.

[16] Furthermore, there is another problem that carbon dust and the like, which are generated in physical treatment processes including the crushing of spent batteries, are discharged into the air to act as new environmental pollutants.

[17] In addition, there is a drawback that the price competitiveness of recycled valuable metals is low due to transportation cost paid to a company of collecting and supplying spent batteries.

[18]

Disclosure of Invention Technical Problem

[19] It is an object of the present invention to provide an apparatus and method for recycling spent zinc-carbon batteries and alkaline batteries, which can reduce transportation cost and thus increase the price competitiveness of recycled and recovered valuable metals, by treating spent batteries through physical and chemical processes in one place with a batch treatment.

[20] Another object of the present invention is to provide an apparatus and method for recycling spent zinc-carbon batteries and alkaline batteries, which can increase the amount of valuable metals to be recovered through chemical treatment, by first removing button-type batteries by shape separation, and efficient separating, through an eddy current separator and an air classifier, metal zinc from zinc, carbon rods, membranes and cases of a large size enough to pass through a size separator.

[21] Still another object of the present invention is to provide an apparatus and method for recycling spent zinc-carbon batteries and alkaline batteries, which can environmentally friendly recover valuable metals using a dust collector and a cooler without generating pollutants.

[22]

Technical Solution

[23] To achieve the above objects, according to one aspect of the present invention, there is provided an apparatus for recycling spent zinc-carbon batteries and alkaline batteries, comprising: a dust collection means for sucking dust generated from crushed spent batteries; a magnetic separation means for separating out magnetic materials from the crushed spent batteries; a size separation means for separating nonmagnetic materials in the crushed spent batteries according to their size; an eddy current separation means for separating zinc and carbon rods from the nonmagnetic materials larger than a given size, which have passed through the size separation means; and a recovery means for collecting valuable metals from the nonmagnetic materials smaller than a given size, which have passed through the size separation means.

[24] According to another aspect of the present invention, there is provided a method for recycling spent zinc-carbon batteries and alkaline batteries, comprising the steps of: sucking dust generated from crushed spent batteries; separating out magnetic materials from the crushed spent batteries; separating nonmagnetic materials in the crushed spent batteries according to their size; separating zinc and carbon rods from the nonmagnetic materials larger than a given size using an eddy current; forming powder after drying the nonmagnetic materials smaller than a given size in an electric furnace; and leaching zinc by adding the powder to an alkaline leaching solution.

[25]

Advantageous Effects

[26] The apparatus and method for recycling spent zinc-carbon batteries and alkaline batteries have an advantage in that dust and hazardous gas, which are generated during physical treatment processes, can be treated in an environment-friendly manner.

[27] Another advantage is that the cost required for recovering valuable metals can be reduced by treating spent batteries through physical and chemical processes in one place with a batch treatment. [28]

Brief Description of the Drawings

[29] FIG. 1 is a schematic diagram of a physical treatment apparatus in the inventive apparatus for recycling spent zinc-carbon batteries and alkaline batteries.

[30] FIG. 2 is a schematic diagram of a shape separation belt according to the present invention.

[31] FIG. 3 is a schematic diagram of a PVC disk according to the present invention.

[32] FIG. 4 is a flow diagram of a physical treatment process in the inventive method for recycling spent zinc-carbon batteries and alkaline batteries.

[33] FIG. 5 is a flow diagram of a chemical treatment process in the inventive method for recycling spent zinc-carbon batteries and alkaline batteries.

[34] FIG. 6 is a schematic diagram of a reactor which is a recovery means according to the present invention.

[35]

[36] [Description of important reference numerals in drawings]

[37] 102: magnetic separation belt; 104: separation-type conveyer belt;

[38] 105: shape separation means; 106: crushing means;

[39] 107: dust collection means; 108: magnetic separation means;

[40] 110: size separation means; 114: eddy current separation means;

[41] 118: electric furnace; and 119: cooling tower

[42]

Mode for the Invention

[43] Description will now be made in detail to the preferred embodiment of the present invention with reference to the attached drawings. Prior to the detailed description of the present invention, it should be confirmed that the terms or words used in the specification and claims of the present invention are construed as meanings and concepts conforming to the technical spirit of the present invention on the basis of a principle that the inventors can define the concept of the term properly for explain their invention with the best method.

[44] Accordingly, the embodiment and drawings of the present specification are no more than one of the preferred embodiments and do not represent all the technological concept of the present invention. In the respect, there may be various equivalents and modifications that can replace the elements illustrated in the specification as of the filing of the present patent application.

[45] FIGS. 1 to 4 show an apparatus and process for physical treating spent zinc-carbon batteries and alkaline batteries according to the present invention.

[46] As shown in FIGS. 1 to 4, spent batteries 101, including alkaline, zinc-carbon, alkaline/zinc-carbon and button-type batteries, are placed on a magnetic separation belt

102. [47] Because spent batteries include waste during the collection process thereof, the waste should first be separated out. The magnetic separation belt 102 separates only spent batteries from waste-containing spent batteries (S20) and transfers the separated spent batteries to a shape separation belt 104. [48] As shown in FIG. 2, the shape separation belt 104 according to the present invention is formed with two polygonal nets 104a and 104b with the diameter larger than that of spent button-type batteries 103 crossed each other at a distance (d) larger than the thickness of the spent button-type batteries, so that other batteries except for button-type ones do not fall into the net holes. [49] The spent batteries 101 except for the spent button-type batteries 103 are sorted by their size in the shape separation means 105 with different net sizes (S21). [50] The spent batteries sorted by their size are passed through a belt to a crushing means 106, in which they are finely crushed (S22). [51] The crushing means 106 is equipped with a dust collection means 107 made of activated carbon, so that it can collect and treat contaminants such as graphite dust generated in the process of crushing the spent batteries through a fan (not shown) in order not to be emitted to the outside (S23). [52] The crushed spent batteries are separated into magnetic materials such as iron scrap

109 and nonmagnetic materials such as zinc, carbon rods and manganese in a magnetic separation means 108 (S24). [53] The nonmagnetic materials are transferred to a size separation means 110, in which they are separated according to their size (S25). The size separation means 110 consists of a vibrating 8-mesh (2.56 mm) screen, and thus separates the nonmagnetic materials into a size of 8 mesh or larger or a size smaller than 8 mesh. [54] Among the nonmagnetic materials of 8 mesh or larger, light plastics, paper, vinyl resins, etc., which have covered the batteries, are transferred to a first reservoir 112 by the suction force of a fan (not shown) connected to the size separation means 110. The first reservoir 112 comprises a pressing means (not shown), which presses plastics, paper and vinyl resins to form a fuel material 113. [55] Heavy carbon rods and zinc plates, which have fallen downward without being sucked by the fan, are passed through a transfer screw (not shown) to an eddy current separation means 114, in which they are separated into carbon rods 115 and zinc plates

116 (S27b). They are highly valuable because they are semi-finished products that can be recycled without any additional reprocessing. [56] Meanwhile, the first reservoir 112 is connected to the dust collection means 107, which sucks dust remaining on the surface of the nonmagnetic materials (S26b). [57] The nonmagnetic fine particles smaller than 8 mesh, which have fallen on the bottom of the size separator, are collected in a second reservoir 117 by a PVC disctype transferring means 111 (S26a).

[58] As shown in FIG. 3, the PVC disc-type transferring means 111 according to an embodiment of the present invention consists of a plurality of PVC discs I l ia connected with each other by a metal wire 11 Ib and a driving gear (not shown).

[59] The PVC discs I l ia collect the nonmagnetic fine particles 111c while rotating by the rotation of the driving gear (not shown). Unlike prior metal screws, the use of the PVC discs does not show a problem of screws' corrosion caused by moisture contained in fine particles to stop the operation thereof.

[60] The nonmagnetic materials smaller than 8 mesh, which are collected in the second reservoir 117, are thermally treated in an electric furnace 118 to remove electrolyte, water and carbon therefrom (S27a).

[61] The electric furnace 118 is of cylindrical shape, able to rotate and inclined at a given angle, so that the nonmagnetic materials can be uniformly thermally treated. Meanwhile, the inclined angle of the electric furnace 118 can be adjusted to control the time required for heat treatment. The heat treatment is done at a temperature of 900-1200 ⁰C.

[62] The second reservoir 117 is connected to a conveyor- type belt so that the button- type spent batteries 103 separated in the shape separation belt 104 can be introduced into the second reservoir. Thus, if treatment for the recycling of spent alkaline, zinc- carbon and alkaline/zinc-carbon batteries is not carried out, spent button-type batteries including spent mercury batteries can be treated.

[63] In the treatment for recycling of spent button-type mercury batteries, mercury in mercury batteries is removed in the form of vapor by thermal treatment in the electric furnace 118, instead of physical crushing.

[64] The electric furnace 118 is connected to a cooling tower 119. Because cooling water flows around the cooling tower 119, mercury vapor or electrolyte vapor generated in the electric furnace 118 can be liquefied so as to prevent the emission of hazardous gas (S28a).

[65] The nonmagnetic materials 120 treated in the electric furnace 118 are used as the raw material of valuable metal Mn-Zn ferrite to be recovered through chemical treatment as described below, and can be prepared into powders through a ball mill (S29a).

[66] FIG. 5 is a flow chart showing a process for chemically treating spent zinc-carbon batteries and alkaline batteries according to the present invention.

[67] The nonmagnetic powder prepared from the above-described physical treatment is mixed with sodium hydroxide (NaOH) as an alkaline leaching solution. In this process, only zinc contained in the nonmagnetic powder is selectively leached (S30), and high purity zinc is recovered from the zinc-leached alkaline solution by electrowinning (S31).

[68] After electrowinning, the remaining alkaline leachate is ready for later use for pH adjustment in subsequent coprecipitation (S35). [69] The residue after the process of recovering zinc is subjected to a process of leaching with sulfuric acid (H SO ) (S32). Carbon and plastics obtained in the sulfuric acid leaching process are discarded and the remaining sulfuric acid leaching solution is recovered for later use as a reaction solution for preparing Mn-Zn ferrite.

[70] Table 1 below shows the composition and acidity of each of the alkaline leachate and the sulfuric acid leaching solution (to be used as reaction solution), which remain after the above steps S31 and S32.

[71] [72] Table 1

[73] [74] The sulfuric acid leaching solution according to the embodiment of the present invention is a reaction solution required for preparing Mn-Zn ferrite powder to be used to obtain a powder of Mn-Zn ferrite at a ratio of zinc: manganese: iron = 1:1:4.

[75] The sulfuric acid leaching solution and the alkaline leachate are mixed to form a necessary reaction solution (S33). To obtain valuable metals at a desired ratio, the component ratio of the sulfuric acid leaching solution is analyzed, and the deficiency is to be supplemented (S34).

[76] Table 2 below shows a stoichiometric molar ratio for making Mn-Zn ferrite powder. [77] [78] Table 2

[79] [80] Table 3 below shows a calculation of deficiency compared with a reaction molar ratio for preparing Mn-Zn ferrite powder.

[81] To supplement deficiency, the reaction molar ratio required for preparing Mn-Zn ferrite powder in 700 ml of the sulfuric acid leaching solution used in the reaction process is calculated.

[82] Then, each concentration of manganese, zinc and iron in 700 ml of the sulfuric acid leaching solution is calculated. [83] According to the embodiment of the present invention, deficiency calculated based on manganese is 0.66 g for zinc and 4.65 g for iron. After electrowinning (S31), the concentration of zinc in the remaining alkaline leachate is 12.45 git, which corresponds to 0.66 g as converted into about 53.2 ml .

[84] Then, the deficiency of zinc is supplemented with the alkaline leachate (leachate concentration 12.45 g/£= 0.66 g/53.2 mf), and the deficiency (23.148g) of iron is supplemented with FeSO4?7H2O (S34).

[85] Then, in order to adjust the acidity (pH) of the leachate to 12, 69 ml of a 4M sodium hydroxide solution is added for coprecipitation (S35). [86] Then, an oxidation step (S36) as a ferrite-bearing reaction (substitution of manganese and zinc with iron oxide) is carried out in a IL reactor (recovery means) on the basis of 700 ml of a reaction solution.

[87] FIG. 6 is a schematic diagram of a reactor as a recovery means according to the present invention. [88] The reactor is equipped with a heater 46, a thermometer 43, a temperature controller 49, a stirrer 48, a motor 41 and a controller 42. Furthermore, it includes a condenser 45 for preventing the evaporation of solution caused by heat treatment, a sampling pipette 47 for injecting a sample, and a clamp 44.

[89] According to the embodiment of the present invention, a surfactant or ultrasonic waves can be used to prevent the aggregation of particles during the formation of ferrite.

[90] [91] Table 3

[92] [93] The oxidation step (S36) is conducted by stirring the sulfuric acid leaching solution at a stirring speed of 400-600 rpm at a temperature of 60-90 ⁰C at atmospheric pressure for 60-100 minutes while supplying 02 into the solution at a flow rate of 0.5-2 I /min. The material obtained from the oxidation step (S36) contains a certain amount of sodium due to sodium hydroxide used to adjust acidity.

[94] A filtration step (S37) is a step of filtering the material formed through the copre- cipitation step (S35) and the oxidation step (S36). In this step, the material formed in the oxidation step (S36) is washed several times with ethanol to remove sodium. [95] According to one embodiment of the present invention, the filtrate remaining after the filtration step (S37) is used as a portion of the alkaline leachate to adjust acidity to 10-14 prior to coprecipitation. [96] According to another embodiment of the present invention, when the recovery of zinc in the electrowinning process is increased, it is possible to use an excess amount of the alkaline leachate to adjust acidity.

[97] The Mn-Zn ferrite powder thus prepared is dried at 95-120 ⁰C for 12-24 hours, yielding a final product (S38). [98] Table 4 below shows results obtained by analyzing the chemical composition of the filtrate remaining after the filtration (S37), using an ICP (inductively coupled plasma) spectrometer.

[99] As shown in Table 4 below, the contents of valuable metals manganese, zinc and iron in the filtrate are low, suggesting that a large amount of valuable metals are recovered.

[100] [101] Table 4

[102] [103] Although the preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[I] An apparatus for recycling spent zinc-carbon batteries and alkaline batteries, comprising: a dust collection means for sucking dust generated in the process of crushing spent batteries; a magnetic separation means for separating out magnetic materials from the crushed spent batteries; a size separation means for sorting nonmagnetic materials in the crushed spent batteries according to size; an eddy current separation means for separating out zinc and carbon rods from the nonmagnetic materials larger than a given size, passed through the size separation means; and a recovering means for recovering valuable metals from the nonmagnetic materials smaller than a given size passed through the size separation means. [2] The apparatus of Claim 1, which further comprises: a shape separation means capable of screening certain size before crushing the spent batteries; and a crushing means for crushing the spent batteries. [3] The apparatus of Claim 2, further comprising a shape separation belt capable of transferring the spent batteries from the outside to the shape separation means. [4] The apparatus of Claim 3, wherein the shape separation belt comprises a plurality of nets for separating spent button-type batteries, which have a given diameter and are formed crosswise. [5] The apparatus of Claim 3, further comprising a magnetic separation belt for separating waste contained in the spent batteries and transferring the batteries to the shape separation belt. [6] The apparatus of Claim 5, wherein the spent batteries include alkaline/ zinc-carbon batteries, zinc-carbon batteries and mercury batteries. [7] The apparatus of Claim 1, wherein the size separation means includes a vibrating mesh screen. [8] The apparatus of Claim 7, wherein the size separation means includes a PVC disc-type transferring means for transferring fine particles. [9] The apparatus of Claim 1, further comprising an electric furnace for removing moisture from the valuable metals. [10] The apparatus of Claim 9, further comprising a cooling tower for liquefying vapor generated in the electric furnace.

[I I] The apparatus of Claim 10, which includes a ball mill means for powdering the moisture-removed valuable metal. [12] A method for recycling spent zinc-carbon and alkaline batteries, comprising the steps of: sucking dust generated in the process of crushing spent batteries; separating magnetic materials from the crushed spent batteries; sorting nonmagnetic materials in the crushed spent batteries according to size; separating zinc and carbon rods from the nonmagnetic materials larger than a given size using an eddy current; forming powder by drying the nonmagnetic materials smaller than a given size in an electric furnace; and leaching zinc by adding the powder to an alkaline leaching solution. [13] The method of Claim 12, further comprising the steps of: separating waste from the spent batteries; separating spent mercury batteries from the spent batteries; and sorting the spent batteries according to size. [14] The method of Claim 13, further comprising a step of sucking dust generated in the process of crushing spent batteries. [15] The method of Claim 12, wherein the powder is formed by ball-milling the dried nonmagnetic materials smaller than a given size. [16] The method of Claim 12, which further comprises the steps of: electrowinning zinc from the zinc-leached alkaline solution; mixing the alkaline leachate with an acid leaching solution; and performing coprecipitation by supplementing the acid leaching solution with the alkaline leaching solution. [17] The method of Claim 16, after the coprecipitation step, further comprising: an oxidation step of oxidizing the produced coprecipitate; a filtration step of filtering the oxide produced in the oxidation step; and a drying step of drying the filtrate. [18] The method of Claim 17, which further comprises, after the step of drying the filtrate, a step of washing the dried material to remove sodium from the dried material. [19] The method of Claim 18, which further comprises a step of reusing the filtrate as a portion of the alkaline leachate for the coprecipitation. [20] The method of Claim 19, wherein the filtrate is adjusted to an acidity of 10 or above by addition of a sodium hydroxide solution containing zinc. [21] The method of Claim 17, wherein a surfactant is used in the filtration step.

[22] The method of Claim 17, wherein ultrasonic waves are used in the filtration step.