JP2003183746A - Process for recovering nickel and cobalt from oxidized ore - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for recovering nickel and cobalt from an oxidized ore containing nickel, cobalt, magnesium and iron. <P>SOLUTION: For leaching nickel and cobalt out of the oxidized ore containing nickel, cobalt, magnesium and iron, a sulfuric acid leachate containing nickel, cobalt, magnesium and a large amount of iron, obtained through leaching with sulfuric acid, is allowed to react with the ore under an atmospheric pressure at a temperature equal to or lower than the boiling point to obtain a reaction liquid containing nickel, cobalt, magnesium and a small amount of iron. The reaction residue of the ore is allowed to react again under an atmospheric pressure at a temperature equal to or lower than the boiling point to recover nickel and cobalt. Compared to a conventional leaching process under ordinary pressure, this process leaches nickel and cobalt at a high efficiency with an extremely small amount of sulfuric acid. It also cuts down the processing cost for removing iron by producing a reaction liquid containing only a small amount of iron. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to nickel, cobalt,
Nickel from oxide ores containing magnesium and iron,
The present invention relates to a method for efficiently, economically, and easily recovering cobalt as a nickel sulfate solution and a cobalt sulfate solution. 2. Description of the Related Art A method for leaching nickel and cobalt from an oxide ore containing nickel, cobalt, magnesium and iron with sulfuric acid is described in Proc. Aust
ralas. Inst. Metall. , No. 26
5, March, 1978 and The metal. S
oc. , 1988, p447,
A normal pressure leaching method for leaching with sulfuric acid under atmospheric pressure to obtain a sulfuric acid solution containing nickel and cobalt;
As described in f Metals, March, 1960, P206, there is a pressure leaching method of leaching with sulfuric acid under high temperature and high pressure. [0003] The Themetal. Soc. 198
As described in FIG. 8, when oxidized ore containing nickel, cobalt, magnesium and iron is leached with sulfuric acid under atmospheric pressure, iron is leached simultaneously with nickel and cobalt, and nickel and cobalt are leached. If it is attempted to leach 80% or more, iron also leach 15% or more. [0004] Generally, an oxide ore containing nickel and cobalt contains 10 to 40 times as much iron as nickel, so that the amount of sulfuric acid required for leaching is increased, and the iron concentration in the leached liquid is high so that iron is removed. The processing cost for removal also increased, which was economically problematic. As a preliminary treatment of an oxide ore containing nickel, cobalt, magnesium and iron, the oxide ore is calcined at a temperature of 600 ° C. or more and then leached with sulfuric acid under atmospheric pressure, whereby the leaching rate of nickel and cobalt is reduced. Be improved. However, the leaching of nickel, cobalt and iron is irrespective of whether ore is not pre-treated,
The consumption of sulfuric acid and the processing cost for removing the leached iron are large, and additional energy for calcining at 600 ° C. or higher is required, which is economically problematic. On the other hand, Journal of Metal
As described in s, when pressure leaching is performed with sulfuric acid under high temperature and high pressure, leaching of iron is suppressed, and a high leaching rate of nickel and cobalt is obtained. Therefore, the amount of sulfuric acid used is small, and the processing cost for removing iron is also small.However, an autoclave is required for sulfuric acid leaching operation under high temperature and high pressure, and the material is expensive such as titanium. Things are needed. In addition, there is a problem that energy consumption increases as compared with leaching under atmospheric pressure. The problem to be solved by the present invention is obtained by leaching with sulfuric acid in leaching nickel and cobalt from an oxide ore containing nickel, cobalt, magnesium and iron. Reacting a sulfuric acid leach solution containing nickel, cobalt, magnesium and a large amount of iron with the ore at a temperature below the boiling point under atmospheric pressure, thereby producing a reaction solution containing nickel, cobalt and magnesium containing only a small amount of iron. Getting
And the reaction residue of the ore is reacted again with sulfuric acid at a temperature below the boiling point under atmospheric pressure, so that nickel and cobalt can be leached at a very small amount of sulfuric acid compared to the conventional atmospheric leaching method. Another object of the present invention is to greatly reduce the processing cost for removing iron by obtaining a solution containing only a small amount of iron. SUMMARY OF THE INVENTION The present invention relates to a method for recovering nickel and cobalt from an oxide ore containing nickel, cobalt, magnesium and iron. Sulfuric acid leaching solution containing nickel, cobalt, magnesium and iron at atmospheric pressure
A normal pressure reaction step (a) in which a reaction solution containing nickel, cobalt, magnesium and iron is obtained by reacting at a temperature of not lower than the boiling point and a nickel, cobalt, magnesium and iron obtained in step (a) A separation step (b) for separating a reaction solution containing
The total amount of the reaction residue obtained in step (b) is
A normal pressure leaching step (c) in which a sulfuric acid leaching solution containing nickel, cobalt, magnesium and iron is reacted with sulfuric acid at a temperature of 80 ° C. or higher and a boiling point or lower, and nickel and cobalt obtained in step (c). Separating the sulfuric acid leachate containing magnesium and iron from the residue, and recycling the sulfuric acid leachate containing nickel, cobalt, magnesium and iron in step (a) (d). A method for recovering nickel and cobalt from a contained oxide ore. Hereinafter, the present invention will be described in detail. The oxide ore used as a raw material in the present invention includes Ni, Co,
Fe, Mg, etc. are contained in the form of oxides, and in mineralogy, limonite ore (also called laterite ore) and saprolite ore (also called garnilite ore) are representative. The general components of limonite ore and saprolite ore are as follows. [Table 1] FIG. 1 shows a process chart for leaching nickel and cobalt from oxide ore. Step (a): Separating oxide ore 1 containing nickel, cobalt, magnesium and iron by a thickener, nickel, cobalt obtained in step (d) of circulating and using sulfuric acid solution,
A normal pressure reaction (a) is performed with sulfuric acid leachate 6 containing magnesium and a large amount (2 to 35 g / l) of iron under atmospheric pressure.
The temperature is preferably higher from the viewpoint of the reaction rate.
It is preferable to carry out at a temperature between ° C and the boiling point. The reaction time is desirably from 1 hour to 10 hours, preferably from 3 hours to 7 hours. In the sulfuric acid leaching solution, nickel, cobalt, magnesium and a large amount (2 to 35 g / l) of iron are present as sulfates, and free sulfuric acid is also present at 5 to 30 g / l. Therefore, when the oxide ore and the sulfuric acid leaching solution are reacted under sufficient stirring, the free sulfuric acid in the sulfuric acid leaching solution is reduced by the reaction of nickel, cobalt, magnesium and sulfuric acid in the oxide ore, and PH is reduced. To rise. With the decrease of the free sulfuric acid, iron contained in a large amount in the sulfuric acid leaching solution precipitates as FeO (OH) to generate sulfuric acid, and at the same time, the sulfuric acid is formed of magnesium in the ore,
It effectively contributes to the reaction with nickel and cobalt, and some of these metals are leached into the reaction solution. By adjusting the pH of the reaction solution to 1.5 to 3.0 and the free sulfuric acid to 0.5 to 5 g / l by the reaction with the oxide ore, the iron concentration is set to 0.1.
It can be reduced to 2 to 2 g / l. Step (b): nickel, cobalt, magnesium obtained in step (a) and a small amount (0.2 to 2.0)
g / l) of iron and a reaction residue 2 of the oxide ore are separated. This separation method includes a solid-liquid separation method using a thickener or a filter press, and the like.
Solid-liquid separation (b) can be easily performed with a thickener. In the reaction solution obtained by overflow from the thickener, a reaction solution 3 containing not more than 2 g / l of iron and not more than 5 g / l of free sulfuric acid in addition to nickel, cobalt and magnesium is obtained. Since both iron and free sulfuric acid have sufficiently low concentrations, removal of iron by neutralization and subsequent recovery of nickel and cobalt are facilitated. In the neutralizing step, calcium is used as a neutralizing agent,
Iron and free sulfuric acid in the reaction solution are precipitated and removed by the use of hydroxides, oxides and carbonates of magnesium and sodium, and at this time, the concentration of iron and free sulfuric acid in the reaction solution at the start of neutralization is sufficiently low. Therefore, the amount of the neutralizing agent used may be small. The neutralized solution thus obtained contains nickel, cobalt and magnesium. To recover nickel and cobalt, the neutralized solution contains sodium bisulfide,
Sodium sulfide, ammonium sulfide, or hydrogen sulfide is added to precipitate and recover as a mixed sulfide of nickel and cobalt (JP-A-6-116660), or mixed hydroxide of nickel and cobalt is added by adding hydroxide, oxide and carbonate. Can be recovered as a product or a mixed carbonate (JP-A-12-234).
130). Magnesium remains in the liquid after precipitation recovery.
On the other hand, the reaction residue 4 is drained from the lower part of the thickener in a slurry state. Step (c): The total amount of the slurry-like reaction residue obtained in step (b) is leached at normal pressure by adding sulfuric acid at a temperature of 80 ° C. or more and a boiling point under atmospheric pressure. By this, nickel, cobalt, magnesium and a large amount (2
A sulfuric acid leach liquor containing (~ 35 g / l) iron is obtained. A normal pressure leaching time between this residue and sulfuric acid is 1 hour or more and 10 hours or less, preferably 3 hours, so that the leaching sufficiently reaches equilibrium. This is because part of nickel, cobalt and magnesium in the oxide ore was leached out by the step (a), and the remaining oxide ore became porous and the surface area was increased. The amount of sulfuric acid used is approximately equivalent to nickel, cobalt and magnesium of the oxide ore,
The pH of the solution is 0.7 to 1.5, and the sulfuric acid solution concentration is 5 to 30 g /
l, so that more than 85% of nickel,
More than 90% of cobalt and magnesium are leached. Step (d): Next, in step (d), step (c)
The sulfuric acid leaching solution containing nickel, cobalt, magnesium and a large amount (2 to 35 g / l) of iron leaching solution obtained in the above is separated from the residue 5. This separation method includes a solid-liquid separation method using a countercurrent washing thickener having six or more stages or a filter press. By adding a polymer flocculant to the slurry and coagulating the slurry, the solid-liquid separation (d) can be easily performed using the thickener. ) Can be performed. The sulfuric acid leachate 6 obtained from the thickener by overflow contains a large amount (2-35 g / l) of iron and 5-
Since 30 g / l of free sulfuric acid is contained, the whole amount is recycled to the step (a), while the residue 7 is drained in a slurry form from the lower part of the thickener and discarded. The residue is an undissolved substance obtained by reacting the reaction residue obtained in the step b with sulfuric acid and leaching most of Ni, Co, Mg and a part of Fe. This residue is completely drained from the bottom of the thickener. The reason is that the residue is Ni,
This is because most of Co is leached and Ni and Co do not remain in the residue. Hereinafter, the present invention will be described specifically with reference to examples. In addition, each component ratio in these examples is wt%.
It is. Table 2 shows the results of Examples and Comparative Examples. Example 1 Ni: 1.49%, Co: 0.026%,
Ni: 3.4 prepared in step (d) using an oxide ore having a composition of 31.1% Fe and 10.8% Mg.
7 g / l, Co: 0.06 g / l, Fe: 12.4 g / l
1, Mg: 27.9 g / l, free sulfuric acid: 12.1 g / l
The sulfuric acid leachate having a concentration of 1 l was stirred and reacted at the boiling point at atmospheric pressure for 6 hours. As a result, the amount of free sulfuric acid in the sulfuric acid leachate was 1
The liquid pH decreased from 2.1 g / l to 2.8 g / l, and the liquid pH rose from 1.02 to 1.69. On the other hand, a part of Ni, Co, and Mg in the ore is leached, and the iron in the sulfuric acid leaching solution is precipitated and removed. Ni: 4.53 g / l, C
o: 0.10 g / l, Fe: 1.29 g / l, Mg: 3
A reaction solution containing only a small amount of iron having a concentration of 9.40 g / l was obtained. At this time, the Fe / Ni ratio (concentration ratio of the liquid) was 0.28. The reaction solution and the reaction residue are coagulated and separated by a thickener, and 98% concentrated sulfuric acid is added to the reaction residue slurry drained from the lower part of the thickener, and the mixture is stirred at the boiling point for 3 hours to leaching Ni, Co, and Mg. I let it. The amount of sulfuric acid added was 0.5 kg per 1 kg of oxide ore. Analysis of the reaction residue revealed that Ni:
0.34%, Co: 0.003%, Mg: 0.82%,
Fe: 42.1%, and the weight reduction ratio of the reaction residue to the ore was 30%. Therefore, the leaching rate is N
i: 84%, Co: 92%, Mg: 95%, Fe: 5%
Met. Example 2 Using the oxide ore of the component used in Example 1, Ni prepared in step (d): 3.42 g / l,
Co: 0.06 g / l, Fe: 10.8 g / l, Mg:
A sulfuric acid leachate having a concentration of 28.9 g / l and a free sulfuric acid of 8.5 g / l was reacted under the same conditions as in Example 1. As a result, the free sulfuric acid in the sulfuric acid leachate was reduced to 1.2 g / l, and the pH of the sulfuric acid leachate was increased from 1.21 to 2.27. On the other hand, Ni in ore,
Part of Co and Mg is leached, and iron in the sulfuric acid leaching solution is precipitated and removed, Ni: 4.89 g / l, Co: 0.10
g / l, Fe: 0.64 g / l, Mg: 38.9 g / l
A reaction solution containing only a small amount of iron having a concentration of was obtained. At this time, the Fe / Ni ratio was 0.13. Thereafter, 98% concentrated sulfuric acid was added to the reaction residue slurry obtained by the thickener separation and leached under the same conditions as in Example 1. The amount of sulfuric acid added was 0.45 kg per 1 kg of oxide ore. Analytical values of the reaction residue,
The leaching rate obtained from the weight loss rate was as follows: Ni: 83%, Co:
93%, Mg: 94%, and Fe: 2%. Example 3 Ni: 1.94%, Co: 0.025%,
Oxide ore having a composition of 24.3% Fe and 15.4% Mg, and 3.34 g / Ni prepared in step (d)
1, Co: 0.05 g / l, Fe: 5.2 g / l, M
g: 28.9 g / l, free sulfuric acid: 10.2 g / l, except that a sulfuric acid leachate having a concentration of 10.2 g / l was used. As a result, the free sulfuric acid in the sulfuric acid leachate was reduced to 0.9 g / l, and the pH of the sulfuric acid leachate was increased from 1.13 to 2.38. On the other hand, Fe /
The Ni ratio was 0.14. Thereafter, 98% concentrated sulfuric acid was added to the reaction residue slurry obtained by the thickener separation in an amount of 0.65 kg per 1 kg of the oxidized ore, and the same procedure as in Example 1 was carried out. Co: 95%, Mg: 94%, F
e: 1%. Example 4 Ni: 1.50%, Co: 0.035%,
Oxide ore having a composition of 19.6% Fe and 25.8% Mg, and 1.89 g / Ni prepared in step (d).
1, Co: 0.04 g / l, Fe: 15.1 g / l, M
g: 28.9 g / l, sulfuric acid: 8.7 g / l, except that a sulfuric acid leachate having a concentration of 8.7 g / l was used. As a result, the free sulfuric acid in the sulfuric acid leachate was reduced to 0.8 g / l, and the pH of the sulfuric acid leachate was increased from 1.24 to 2.45. On the other hand, the reaction solution Fe
The / Ni ratio was 0.28. Then, 0.65 kg of 98% concentrated sulfuric acid was added to 1 kg of oxide ore to the slurry of the reaction residue obtained by thickener separation, and the same procedure as in Example 1 was carried out. As a result, the leaching rate was 92% for Ni: 92%. Co: 90%, Mg: 94%, F
e: 0.4%. Comparative Example 1 Oxide ore of the component used in Example 1 was slurried with water, and 98% concentrated sulfuric acid was added.
The mixture was stirred and reacted at atmospheric pressure for 6 hours. The amount of sulfuric acid added was 0.5 kg per 1 kg of oxidized ore in the same amount as in Example 1. Analysis of the reaction residue showed that Ni:
1.20%, Co: 0.022%, Mg: 5.8%, F
e: 39.3%, and the weight reduction ratio of the reaction residue to the ore was 29%. Therefore, the leaching rate is Ni:
43%, Co: 40%, Mg: 62%, and Fe: 10%. The leachate concentration was 1.62 g / l Ni, C
o: 0.028 g / l, Mg: 17.0 g / l, Fe:
7.9 g / l, free sulfuric acid: 27.6 g / l, F
Both the e / Ni ratio and the free sulfuric acid concentration increased. Comparative Example 2 Oxide ore of the component used in Example 2 was slurried with water, and then 0.95 kg of 98% concentrated sulfuric acid was added to 1 kg of oxide ore at a boiling point and at atmospheric pressure. The mixture was stirred and reacted for 6 hours. Analysis of the reaction residue showed that N
i: 0.53%, Co: 0.008%, Mg: 1.1
%, Fe: 26.3%, and the weight loss of the reaction residue with respect to the ore was 41.5%. Therefore, the leaching rate was as follows: Ni: 84%, Co: 8
The leaching rate was as high as 2% and Mg: 96%.
The leaching rate was as high as 6%. This leachate concentration is Ni:
4.13 g / l, Co: 0.052 g / l, Mg: 3
6.5 g / l, Fe: 21.6 g / l, free sulfuric acid: 4
It was 3.3 g / l, and both the Fe / Ni ratio and the free sulfuric acid concentration increased. Comparative Example 3 Oxide ore of the components used in Example 4 was slurried with water, and 1.30 kg of 98% concentrated sulfuric acid was added to 1 kg of oxide ore, and the reaction was carried out in the same manner as in Comparative Example 1. . The leaching rate was as high as 89% for Ni, 86% for Co, and 90% for Mg, but also 43% for iron.
The leachate concentration was as follows: Ni: 2.67 g / l, Co: 0.
06 g / l, Mg: 46.4 g / l, Fe: 15.5 g
/ L, free sulfuric acid: 45.2 g / l, Fe / Ni
Both the ratio and the free sulfuric acid concentration increased. [Table 2] According to the present invention, nickel, cobalt,
Nickel from oxide ores containing magnesium and iron,
When leaching cobalt, a high leaching rate of nickel and cobalt can be obtained with a small amount of sulfuric acid, and a reaction solution containing only a small amount of iron can be obtained, so that nickel and cobalt can be efficiently leached economically. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process chart of leaching nickel and cobalt from oxide ore. [Description of Signs] a Atmospheric pressure reaction step b Thickener separation step c Atmospheric pressure leaching step d Thickener separation, sulfuric acid leachate circulating use step 1 Oxide ore 2 Reaction liquid + reaction residue 3 Reaction liquid 4 Reaction residue 5 Sulfuric acid leachate + residue Thing 6 sulfuric acid leachate 7 residue

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kazuhiko Miura             Hachinohe City, Aomori Prefecture               Taiheiyo Metal Co., Ltd. F term (reference) 4K001 AA07 AA19 BA02 DB03

Claims (1)

Claims: 1. To recover nickel and cobalt from an oxide ore containing nickel, cobalt, magnesium and iron, (1) the nickel or cobalt obtained in the step (d) with the oxide ore A sulfuric acid leaching solution containing magnesium, iron and iron at atmospheric pressure at a temperature of 80 ° C. or more and a boiling point or less to obtain a reaction solution containing nickel, cobalt, magnesium and iron, and an atmospheric pressure reaction step (a); ) Separation step (b) for separating the reaction solution containing nickel, cobalt, magnesium and iron obtained in step (a) from the reaction residue of the oxide ore, and (3) obtained in step (b). Atmospheric pressure leaching step in which the total amount of the reaction residue is reacted with sulfuric acid at atmospheric pressure at a temperature of 80 ° C. or higher and a boiling point or lower to obtain a sulfuric acid leaching solution containing nickel, cobalt, magnesium and iron (c).
And (4) the nickel, cobalt obtained in step (c),
Separating the sulfuric acid leachate containing magnesium and iron from the residue, and recycling the sulfuric acid leachate containing nickel, cobalt, magnesium and iron in step (a) (d). A method for recovering nickel and cobalt from contained oxide ores.