JPS5953358B2 - Manufacturing method of cobalt powder by electrolysis method - Google Patents

Description

【発明の詳細な説明】 本発明は高純度のコバルト粉を電解的に製造する方法に
関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for electrolytically producing high purity cobalt powder.

コバルト粉は主として超硬合金用のバインダー、焼結合
金磁石、触媒等として近年需要が伸びつ・あるものであ
る。Demand for cobalt powder has been increasing in recent years, mainly as a binder for cemented carbide, sintered alloy magnets, catalysts, etc.

これらの用途に用いられるコバルト粉は、高純度である
だけでなく粒度の小さいものが望まれており特に超硬合
金用としては酸素含有量が０．４５重量％以下が好まし
いとされている。The cobalt powder used for these applications is desired to have not only high purity but also small particle size, and it is said that an oxygen content of 0.45% by weight or less is particularly preferable for use in cemented carbide.

電解法によるコバルト粉の製造法としては従来硫酸電解
溶による方法が提案されているが、この方法は細かい粉
末は得られるけれども粗粒や水酸化物の生成を抑制して
、微粉を得るための電解条件すなわち陰極電流密度、電
解液のｐＨおよび濃度等に厳しい制約があるため、その
実用範囲が挟く限定される。As a method for producing cobalt powder by electrolytic method, a method using sulfuric acid electrolytic dissolution has been proposed, but although this method can obtain fine powder, it is difficult to obtain fine powder by suppressing the generation of coarse particles and hydroxide. Since there are severe restrictions on electrolysis conditions, such as cathode current density, pH and concentration of the electrolytic solution, its practical range is severely limited.

又比較的摺電圧が高くなるため、電解コストが高くなり
、同時に工業的規模の操業では電解液の温度が上昇する
等多くの問題点がある。硫酸電解溶によるコバルト粉の
製造においては、一般に電流密度、電解液の濃度、ｐＨ
あるいは温度等によつて粉末状コバルト金属の析出状態
が異なつてくる。微粉状の電解粉末を得るためには溶液
濃度は大きくない方が良く、又ｐＨは中性に近い方が好
ましい。しかし電解条件が適当でないと水酸化物が混入
してコバルト粉の収率が低下する。電解の操作中には水
素の発生に依つて水酸化物が生成してｐＨの上昇が見が
れる（硫酸浴の場合には、この現象が激しい）。これを
抑制するため１０〜３０ｇハの硫酸アンモニウム、硼酸
等の添加剤添加が必要であることは周知のごとくである
。本発明の目的は上記のような問題点のない、コバルト
粉の製造法を提供することである。Furthermore, since the sliding voltage is relatively high, the cost of electrolysis increases, and at the same time, there are many problems such as an increase in the temperature of the electrolytic solution in industrial scale operation. In the production of cobalt powder by sulfuric acid electrolysis, current density, electrolyte concentration, pH
Alternatively, the state of precipitation of the powdered cobalt metal varies depending on the temperature and the like. In order to obtain a finely divided electrolytic powder, the solution concentration should not be high, and the pH should preferably be close to neutral. However, if the electrolytic conditions are not appropriate, hydroxides will be mixed in, reducing the yield of cobalt powder. During the electrolysis operation, hydroxide is generated due to the generation of hydrogen, and an increase in pH is observed (this phenomenon is severe in the case of a sulfuric acid bath). It is well known that in order to suppress this, it is necessary to add 10 to 30 g of additives such as ammonium sulfate and boric acid. An object of the present invention is to provide a method for producing cobalt powder that does not have the above-mentioned problems.

然して本願発明者らは研究の結果、塩酸電解浴において
比較的純度の高いコバルトを陽極とし、ステンレス等の
耐蝕性材料、又は電気コバルトあるいは電気ニッケルの
板を陰極として用い、適正な電解条件を与えるとによつ
て、粗粒又は板状の金属を析出させることなく、陰極に
微細粒子のコバルト粉を析出することを見出した。そし
て、このように電解の操作中、陰極に粗粒又は板状の金
属を析出させずかつ水酸化物の生成を抑制するごとき電
解液のｐＷ陰極電流密度（以下ＤＫ■Ａ／ｄｍ・と略称
フする）、塩化コバルト電解液中のコバルト濃度および
温度等の関係を究明して本発明の電解法よるコバルト粉
の製造法を達成した。次に、本発明をさらに詳しく説明
する。However, as a result of research, the inventors of the present application found that in a hydrochloric acid electrolytic bath, relatively pure cobalt was used as an anode, and a corrosion-resistant material such as stainless steel, or a plate of electrolytic cobalt or electrolytic nickel was used as a cathode to provide appropriate electrolytic conditions. It was discovered that fine particles of cobalt powder can be deposited on the cathode without depositing coarse grains or plate-like metal. During the electrolysis operation, the pW cathode current density (hereinafter abbreviated as DK A/dm) of the electrolyte is such that coarse particles or plate metals are not deposited on the cathode and hydroxide generation is suppressed. By investigating the relationship between the cobalt concentration and temperature in a cobalt chloride electrolyte, we have achieved a method for producing cobalt powder by the electrolytic method of the present invention. Next, the present invention will be explained in more detail.

コバルト濃度１０ｇハ以下、好ましくは１〜５ｇハの微
塩ｉ酸酸性塩化コバルト水溶液（必要により２０〜３０
ｇ／ｌ（７）ＮＨ、Ｃｌ又はＮａＣｌを添加してもよい
。）を電解浴とし、陽極には高純度の電気コバルト板、
陰極にはステンレス又はコバルト、ニツケルの板を併列
にした両極平板式又は回転円筒陰極式、回転円盤陰極式
、両極回転円筒式等として使用して通常の電解操作を行
う。この間電解液は循環させながら、あるいは循環しな
いで、塩酸水溶液を添加してＰＨを３〜７、好ましくは
５〜６に調整し、ＤＫ＝７Ａ／Ｄｍ倉以下、好ましくは
１〜５Ａ／Ｄｍ＼液温は８０℃以下に保持して直流電解
を行う。塩化コバルト電解液のコバルト濃度を１０ｇハ
以上に限定した理由は、該濃度が１０ｇハ以下になると
微細粒子のコバルト粉が得られないからであり、また、
ＰＨを３〜７に限定した理由はＰＨが３以下では第１図
のＰＨ，ＤＫ、コバルト濃度と生成物との関係に示した
ように、粉状の金属が得られず、通常の電解のように銀
白色の金属が陰極面に一面に析出するからでありまたＰ
Ｈ７以上では、特に図示していないが、水酸化物の生成
が激増するからである。ＤＫ７以上では、電解液のコバ
ルト濃度が特に高濃度の場合、得られるコバルト粉が粗
粒となり、かつ摺電圧が高くなり、強制冷却を必要とす
る程液温が上昇する。液温は８０℃以下が好ましい。一
般に液温は生成するコバルト粉の性状に及ぼす影響は比
較的少い。しかし適度な温度は粉末の剥離を良好にし、
粉末の得られる範囲を広くするがあまり高温に過ぎると
コバルト粉が粗，粒化する傾向があり又電解浴の損傷や
ミストの発生等トラブルの原因となる。陰極側に生成す
るコバルト粉は、軽く掻き落す方式でも自然落下方式と
しても良いが、何れの場合でも、表面が平滑な例えばス
テンレス板５（ＳＵＳ−３０１）のように剥離性の良い
ものを使用することが望ましい。A slightly acidic cobalt chloride aqueous solution with a cobalt concentration of 10 g or less, preferably 1 to 5 g (20 to 30 g if necessary)
g/l (7) NH, Cl or NaCl may be added. ) is used as an electrolytic bath, and the anode is a high-purity electric cobalt plate,
A bipolar flat plate cathode type, a rotating cylinder cathode type, a rotating disk cathode type, a bipolar rotating cylindrical cathode type, etc. in which stainless steel, cobalt, or nickel plates are arranged in parallel are used as the cathode, and normal electrolytic operations are performed. During this time, the electrolyte is circulated or not, and an aqueous hydrochloric acid solution is added to adjust the pH to 3 to 7, preferably 5 to 6, and DK = 7 A/Dm or less, preferably 1 to 5 A/Dm. Direct current electrolysis is performed while maintaining the liquid temperature at 80° C. or lower. The reason why the cobalt concentration of the cobalt chloride electrolyte is limited to 10 g or more is that if the concentration is less than 10 g, fine particle cobalt powder cannot be obtained, and
The reason for limiting the PH to 3 to 7 is that when the PH is 3 or less, as shown in the relationship between PH, DK, cobalt concentration, and products in Figure 1, powdered metal cannot be obtained, and normal electrolysis is difficult. This is because a silvery-white metal is deposited all over the cathode surface, and P
This is because at H7 or higher, although not particularly shown in the figure, the production of hydroxide increases dramatically. At DK7 or higher, when the cobalt concentration of the electrolytic solution is particularly high, the obtained cobalt powder becomes coarse particles, the sliding voltage becomes high, and the liquid temperature rises to the extent that forced cooling is required. The liquid temperature is preferably 80°C or lower. Generally, the liquid temperature has relatively little effect on the properties of the cobalt powder produced. However, moderate temperature facilitates powder exfoliation,
Although the range in which the powder can be obtained is widened, if the temperature is too high, the cobalt powder tends to become coarse and granular, which may cause problems such as damage to the electrolytic bath and generation of mist. The cobalt powder generated on the cathode side can be scraped off lightly or allowed to fall naturally, but in either case, use a material with a smooth surface and good removability, such as stainless steel plate 5 (SUS-301). It is desirable to do so.

本発明の方法は第１〜２図のＰＨ、コバルト濃度、ＤＫ
（Ａ／Ｄｍ２）の関係に示されるように、従来法と比較
して電解条件がはるに広い。The method of the present invention is based on the PH, cobalt concentration, and DK shown in Figures 1 and 2.
As shown in the relationship (A/Dm2), the electrolytic conditions are much wider than in the conventional method.

これは主として硫酸浴の場合には水素を発生し易く、そ
のため第３図に見らるように、水酸化物のみの生成領域
が存在するが、本発明の場合には、上記よりはるかに、
水素が発生し難いので水酸化物のみの生成領域はなく、
又低ＤＫ領域に於４ては硫酸浴では直ちに金属の生成が
見られるが本発明ではコバルト濃度によつては金属の生
成しない領域が認められる。This is mainly due to the fact that hydrogen is easily generated in the case of a sulfuric acid bath, and therefore, as shown in Figure 3, there is a region in which only hydroxide is generated, but in the case of the present invention, hydrogen is generated much more than the above.
Since it is difficult to generate hydrogen, there is no region where only hydroxides are generated.
Further, in the low DK region 4, metal formation is immediately observed in the sulfuric acid bath, but in the present invention, depending on the cobalt concentration, there are regions where metal is not formed.

また本発明における塩酸浴は後述の実施例に見られるよ
うに硫酸浴と比較してＤＫ（Ａ／Ｄｍつに関連する摺電
圧が１／２〜１／３と低く電流効率もほ・゛同等である
からコスト的に安く経済的な方法と言うことができる。In addition, as seen in the examples described later, the hydrochloric acid bath in the present invention has a sliding voltage related to DK (A/Dm) of 1/2 to 1/3, which is 1/2 to 1/3 lower than that of a sulfuric acid bath, and the current efficiency is almost the same. Therefore, it can be said that it is a low-cost and economical method.

本発明において摺電圧が上記のように低くなる理由につ
いては、主としてその電気電導度が塩酸浴９５．０硫酸
浴６６．０オーム−１×Ｃｍ−１（ＣＯＯ．Ｏ３８当量
、２５℃）と大差があるためと思われる。又さらに摺電
圧を下げるために３０ｇハ程度の・ＮＨ４Ｃｌ又はＮａ
Ｃｌを添加することもできる。The reason why the sliding voltage is so low in the present invention as described above is mainly due to the large difference in electrical conductivity between the hydrochloric acid bath 95.0 and the sulfuric acid bath 66.0 ohm-1×Cm-1 (COO.O38 equivalent, 25°C). This seems to be because there is. Also, in order to further lower the sliding voltage, add about 30 g of NH4Cl or Na.
Cl can also be added.

本発明で得られるコバルト粉の粒度は１００メツシユ以
下が５０〜８０％であるが、これはそのま・適当な湿式
粉砕を行つて１００メツシユ以下とし、空気を吸蔵しな
いような乾燥を施して製品とする。以下実施例について
説明する。The particle size of the cobalt powder obtained in the present invention is 50 to 80% less than 100 mesh, but this can be reduced to less than 100 mesh by appropriate wet grinding and dried to prevent air occlusion. shall be. Examples will be described below.

実施例 １ アノードとして１５０ｍｍ×２００ｍｍ×１０ｍｍの電
気コバルト板２枚（ＣＯ９９．５重量％、ＮｉＯ．２±
０．１１重量％）、カソードには１６０Ｉｎｍ×２５０
［Ｎｎｌ×３ｍｍの電気二ツケル板１枚を極間距離３０
ｍｍとして幅１２０ｍｍ長さ２００ｍｍ高さ（資）偏ｍ
の電解槽にセツトし、コバルト濃度１．７ｇ／１ＰＨ６
．０の塩化コバルト水溶液を槽内に満した。Example 1 Two 150 mm x 200 mm x 10 mm electric cobalt plates (99.5% by weight of CO, 2±2% of NiO) were used as anodes.
0.11% by weight), 160 Inm x 250 for the cathode
[One Nnl x 3mm electric Nitsukel board with a distance between poles of 30
Width 120mm Length 200mm Height (capacity) deviation m
Cobalt concentration 1.7g/1PH6
．． 0 cobalt chloride aqueous solution was filled in the tank.

電解槽の出口から水溶液の一部をオーバーフロー方式で
抜取り循環させ、ＤＫ、３Ａ／Ｄｍ含、２４Ａの電流を
通じ、液温３０〜４０℃に保持しながら約２９時間電解
的にアノードを溶解し、５８２ｇスポンジ状コバルト粉
を得た。A part of the aqueous solution is extracted from the outlet of the electrolytic cell using an overflow method and circulated, and a current of 24 A, including DK, 3 A/Dm, is passed through the solution, and the anode is electrolytically dissolved for about 29 hours while maintaining the liquid temperature at 30 to 40°C. 582 g of spongy cobalt powder was obtained.

得られた粉の粒度は１００メツシユ以下が８０重量％で
あつたが、薄い塩酸水溶液で軽く水洗を行つたのぢ振動
ミルによつて２分間の湿式粉砕を行つたところ、オール
１００メツシユ以下となり、直ちに豪乾燥を行つたとこ
ろ酸素含有量は０．３２重量％あつた．−，肯電解操作
中は稀塩酸を使用してＰＨは６．０に保持したがその摺
電圧は１０．０Ｖ、電流効率は７５．７％゛であつた。The particle size of the obtained powder was 80% by weight of 100 mesh or less, but when it was wet-pulverized for 2 minutes in a vibrating mill after being lightly washed with dilute hydrochloric acid aqueous solution, the particle size was all 100 mesh or less. When drying was carried out immediately, the oxygen content was 0.32% by weight. - During the positive electrolytic operation, the pH was maintained at 6.0 using dilute hydrochloric acid, and the sliding voltage was 10.0 V and the current efficiency was 75.7%.

豪乾燥方法 湿式粉砕されたコバルト粉は直ちに５％コータミン水溶
液（花王アトラス製、商品名一カチオン系界面活性剤、
コータミン２４−Ｐ）中に移し入れ、コーテイングを行
つてから、窒素雰囲気とした乾燥器で３５０℃１時間乾
燥したのち窒素雰囲気中で冷却する。Australian Drying Method Wet-pulverized cobalt powder is immediately treated with a 5% Cortamine aqueous solution (manufactured by Kao Atlas, trade name monocationic surfactant,
The sample was transferred to Coatamine 24-P) and coated, dried in a dryer at 350° C. for 1 hour in a nitrogen atmosphere, and then cooled in a nitrogen atmosphere.

実施例 ２ アノードとした５０ｍｍ×６０ｍｍＸ１０ｍｍの電気コ
バルト枚（実施例１に使用のもの）、カソードには８０
ｍｍ×８０ｍｍ×３ｍｍ（７）ＳＵＳ−３０１の板、各
１枚を極間距離３０ｍｍとして直径１０５ｍｍ深さ１５
０ｍｍの１１ガラスビーカ一にセツトし、コバルト濃度
５ｇ／１ＰＨ３．０の塩化コバルト溶液を満し液温を３
０℃に調整し、ＤＫ＝５Ａ／Ｄｍ２電流６．４Ａとした
ほかは実施例１と同様に約１０時間処理したところ５５
ｇのコバルト粉を得た。Example 2 An electric cobalt sheet of 50 mm x 60 mm x 10 mm (used in Example 1) was used as an anode, and 80 mm was used as a cathode.
mm x 80 mm x 3 mm (7) SUS-301 plates, each with a distance between poles of 30 mm, diameter 105 mm and depth 15
Set it in a 0 mm 11 glass beaker, fill it with a cobalt chloride solution with a cobalt concentration of 5 g/1PH 3.0, and raise the temperature to 3.
When treated for about 10 hours in the same manner as in Example 1 except that the temperature was adjusted to 0°C and the DK = 5A/Dm2 current was 6.4A, the result was 55
g of cobalt powder was obtained.

得られ粉は１００メツシユ以下が５３重量％で水洗後、
２分間の振動ミル粉砕で７０重量％に増加し、乾燥を終
つた製品の酸素含有量は０．３０重量％であつた。尚摺
電圧は５．１Ｖ、電流効率は７８．１％であつた。比較
例 １ 電解浴を硫酸浴とし、実施例２と同じ装置で電解条件は
コバルト濃度５ｇハの硫酸コバルト水溶液のＰＨ３．Ｏ
、ＤＫ＝５Ａ／Ｄｍ２電流６．４Ａと、実施例２とほ）
゛同様にして処理したところ得られた粉は１００メツシ
ユ以下が４７重量％で摺電圧は１３．４Ｖと高く電解効
率は７９．２％と実施例２とほ）゛同様であつた。The resulting powder contains 53% by weight of 100 mesh or less, and after washing with water,
Vibratory milling for 2 minutes increased the oxygen content to 70% by weight, and the dried product had an oxygen content of 0.30% by weight. The sliding voltage was 5.1 V, and the current efficiency was 78.1%. Comparative Example 1 The electrolytic bath was a sulfuric acid bath, the same equipment as in Example 2 was used, and the electrolytic conditions were a cobalt sulfate aqueous solution with a cobalt concentration of 5 g, pH 3. O
, DK=5A/Dm2 current 6.4A, and Example 2)
When treated in the same manner, the powder obtained had 47% by weight of 100 mesh or less, the sliding voltage was as high as 13.4V, and the electrolytic efficiency was 79.2%, which was similar to Example 2).

比較例 ２ 塩化コバルトのコバルト濃度１．５ｇ／１ｐＨ２．０Ｄ
Ｋ−１Ａ／Ｄｍ・、常温、とした以外は実施例２と同様
にして処理したところコバルトは平板状、一部粒状電着
となり、粒状のものだけ振動ミルで２分間づつ５回湿式
粉砕したがその大部分が１００メツシユ以上に止まつた
。Comparative Example 2 Cobalt concentration of cobalt chloride 1.5g/1pH2.0D
When treated in the same manner as in Example 2 except that K-1A/Dm was used at room temperature, the cobalt was electrodeposited in the form of a flat plate and partially in the form of granules, and only the granules were wet-pulverized 5 times for 2 minutes each in a vibrating mill. However, most of them stayed at over 100 meshes.

比較例 ３ 電波液のＰＨ７．５とした以外は比較例２と同じ条件で
処理したところ著るしい水酸化物の生成が見られコバル
ト粉の生成はほとんど見られなかつた。Comparative Example 3 When processing was carried out under the same conditions as in Comparative Example 2 except that the pH of the radio wave liquid was adjusted to 7.5, significant hydroxide formation was observed, and almost no cobalt powder formation was observed.

【図面の簡単な説明】[Brief explanation of drawings]

第１，第２および第３図はいづれも電解浴のＰＨおよび
コバルト濃度および電流密度とコバルト析出状態の関係
を示す図である。 第１図は塩酸浴、第２図は３０ｇハのＮＨ４Ｃｌを添加
した塩酸浴、第３図は硫酸電解浴の場合である。図中×
は板状、○スポンジ状の析出を示し△は水酸化部の生成
を示す。1, 2, and 3 are diagrams showing the relationship between the pH of the electrolytic bath, the cobalt concentration, the current density, and the state of cobalt precipitation. FIG. 1 shows a hydrochloric acid bath, FIG. 2 shows a hydrochloric acid bath to which 30 g of NH4Cl has been added, and FIG. 3 shows a sulfuric acid electrolytic bath. × in the diagram
◯ indicates plate-like precipitation, ○ indicates spongy precipitation, and △ indicates the formation of hydroxylated parts.

Claims (1)

【特許請求の範囲】[Claims] １ 高純度のコバルトを陽極とし、コバルト濃度１０ｇ
／ｌ以下の塩化コバルト水溶液を電解液としてｐＨ３〜
７、陰極電流密度７Ａ／ｄｍ＾２以下において電解を行
うことから成る電解法によるコバルト粉の製造法。1 High purity cobalt is used as an anode, cobalt concentration 10g
/l or less cobalt chloride aqueous solution as electrolyte with pH 3~
7. A method for producing cobalt powder by an electrolytic method comprising carrying out electrolysis at a cathode current density of 7 A/dm^2 or less.