JPH01104729A - Method for smelting co crust - Google Patents

Abstract

PURPOSE:To easily recover high-purity Ni, Co, and Cu by applying two-stage leaching to Co crust by means of an aqueous solution of sulfurous acid, blowing air into the leach liquor and neutralize it with Ca(OH)2, and subjecting the above to two-stage treatment with MgO and then to treatment with NH4OH. CONSTITUTION:Mn content in Co crust is dissolved with an aqueous solution of sulfurous acid, and excess sulfurous acid content is consumed by the addition of Co crust. Fe in the resulting leach liquor is oxidized by air and neutralized with Ca(OH)2, by which Fe is separated. MgO is added to the resulting iron- removed liquor to raise pH and obtain hydroxides of Ni, Co, and Cu, and further, MgO is added to the filtrate to obtain hydroxides of Ni, Co, and Cu. These hydroxides are dissolved by means of (NH4)2CO3-containing aqueous NH4OH, and steam is blown into the resulting solution, by which NH4OH is recovered and basic carbonates of Ni, Co, and Cu is prepared. Subsequently, treating is applied by the conventional methods, by which Ni, Co, and Cu are recovered respectively. By this method, valuable metals, such as Ni, Co, and Cu, can be easily recovered in high purity.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for smelting Co crust.

Co crust has recently been rapidly attracting attention in Western countries and Japan as the third deep-sea mineral resource following manganese nodules and submarine hydrothermal deposits. C.

Crust is distributed in layers with a thickness of several u to lO (1) on the slopes and flat tops of relatively old seamounts on relatively shallow seabeds with depths of 800 to 2,400 m.
It is estimated that it covers 0%. - The Co crust components in the shell are NiO, 2-0.8%, Co 0.3-1.
2%, Cu0.03-0.3%, Fe5-20%,
The Mn content is in the range of 18 to 30%, and the Co content is particularly high compared to manganese nodules, and its quality is extremely high, 10 times that of terrestrial resources, and it has been confirmed that it exists in large quantities over a wide area. A US study found that 20% of the US
Just within the 0 nautical mile zone, 20,000 years worth of CO is consumed in Japan.
Co is said to be contained in the same deposit, and it has been attracting a lot of attention in Japan, which is poor in Co resources.

(Prior Art) Regarding the smelting technology of Co crust, it is considered that the key point is how to establish an economical smelting method. Co-crust smelting methods are broadly classified into pyrometallurgical smelting and hydrometallurgical smelting.

In the pyrometallurgical method, Co crust is charged into a refractory furnace together with additives such as reducing agents and chlorinating agents, and is heated to a high temperature or molten state using electrical energy or fuel energy, and its physical and chemical properties are then controlled. Although this method attempts to separate and recover various metals by utilizing the differences in the C
o The crust is physically, chemically, and mineralogically very complex, and is characterized by containing various metals.
It is considered impossible to separate and refine all the contained metals using only the pyrometallurgical method. In addition, the pyrometallurgy method still has problems that need to be solved from the viewpoints of energy conservation and equipment costs. .

On the other hand, in the hydrometallurgical method, Co crust is directly leached with acid or alkali, and each metal is purified and separated by precipitation, solvent extraction, ion exchange, electrolysis, etc., either singly or in combination. The purpose is to recover the metals that are The main hydrometallurgical methods currently being researched include sulfuric acid leaching, hydrochloric acid leaching, and ammonia leaching.

The sulfuric acid leaching method is being researched not only in Japan but also in other countries because sulfuric acid is an inexpensive reagent. A problem with the sulfuric acid leaching method below the boiling point (from normal temperature to the boiling point) is that the leaching rate of CO is low.

On the other hand, in the sulfuric acid leaching method under high temperature and pressure, it is possible to increase the leaching rate of Co together with Cu and Ni while suppressing the dissolution of Fe and Mn. Most of the sulfuric acid is consumed in dissolving Mg-based minerals, and it is difficult to recycle the sulfuric acid, resulting in a large amount of sulfuric acid consumption. Further, although drying, reduction equipment, etc. are not required, investment in corrosion-resistant equipment remains a major problem since the reaction is at high temperature and high pressure.

The characteristics of the hydrochloric acid leaching method are that Ni, Ni,
It is said that in addition to Co and Cu, all metals such as Fe and Mn are leached out. Currently, metals other than Nil Co and Cu, which are the metals that are particularly desired to be recovered, are also leached out, so there is a drawback that the amount of hydrochloric acid consumed is large. Furthermore, although the hydrochloric acid leaching method does not require high temperature or high pressure, it does require heating to about 90° C., and requires measures to recover and utilize chlorine gas and corrosion-resistant equipment.

In the ammonia leaching method, it has been shown that valuable metals such as Nil Cot Cu in Co crust cannot be recovered at a high leaching rate using only ammonia and ammonium salt. For this reason - the use of reducing agents such as carbon oxide, Cu
(II) Studies have been made to obtain a high leaching rate by a method called the Cuprion method, which utilizes the catalytic action of ions. Ammonia is considered to have many advantages such as being recyclable and non-corrosive to equipment, but Ni
Although the leaching rate of Cu is high at 90% or more, the leaching rate of CO is low at about 50%, which is considered to be a drawback.

On the other hand, the characteristics of the reduction leaching method of Co crust using sulfite water adopted in the present invention are that the reaction is carried out at room temperature and pressure;
The leaching rate is fast, the leaching rate of Ni, Co, and Cu is high (the leaching rate of Fe is low), and there is no need to take special consideration to the corrosion resistance of the equipment, and reaction vessels such as stainless steel and FRP can be used.

Ni, Co, which are valuable metal components in Co crust,
Cu is on average approximately 0.5% and 0.7% each in the Co crust.
and 0.2%. Due to this relatively low content, it is extremely difficult to obtain a purified liquid with a high concentration that can be used industrially when processed using normal methods.
It is considered difficult to efficiently produce Nil Co and Cu in subsequent steps.

(Problems to be Solved by the Invention) One of the objects of the present invention is to sequentially purify and separate Co crust based on a sulfite leaching method to obtain high-purity Ni and Co.
, to provide a complete method for producing Cu.

Still another object of the present invention is to provide a method for separating, disposing of, or storing metals other than Ni, Co, and Cu contained in Co crust in a chemically stable form that does not become a pollution source. It is.

(Means for Solving the Problems) The method of the present invention will be explained below based on the process chart shown in FIG.

(In the leaching step 11, the Co crust crushed into 100 meshes or less is leached using sulfurous acid water at room temperature for 10 to 30 minutes. At this time, the Co crust is leached in two stages.

In the first leaching process, 1.2 to 2.5 times the chemical equivalent of sulfite water is added to dissolve the Mn content in the Co crust in order to promote the reaction and increase the leaching rate of each metal. leach. If the amount of sulfite water is less than 1.2 equivalents, N
The leaching rate of t, Co+Cu is poor, and the reaction rate is also slow. Furthermore, if the amount of sulfite water exceeds 2.5 equivalents, the following treatment steps will become complicated. In the second leaching step, a Co crust of firewood is added and leached in order to consume the excess sulfite remaining in the first leaching filtrate. At this time, this Co' crust is not completely leached out, so it is returned to the first leaching process. The leaching residue from the first stage mainly contains undissolved Fe and M.
n minutes remain.

(2) In the oxidation step, Fe(If) ions in the leachate are oxidized to Fe(III) ions by air blowing, and at the same time, sulfites are completely converted to sulfates. this is,
In the next step, Fe is neutralized with Ca (Off) t and F
This is done in order to be able to stably separate and recover Ni, Co, and Cu in the following process by making them separable as e(011)s and converting sulfite to sulfate.

(3) In the neutralization step with Ca (OH) 2, the air-oxidized liquid is neutralized with Ca (0) 1) z so that the pH is in the range of 2 to 4.0. As a result, the Fe content in the liquid can be precipitated and separated as ferric hydroxide. Furthermore, the free sulfuric acid produced in the previous step is consumed, and the amount of MgO consumed in the next MgO neutralization step is reduced.

(41 In the MgO neutralization (-stage) step, MgO is added to the liquid after iron removal to raise the pH to 7.8 to 8.5 and Ni.

Co and Cu are converted into hydroxides and separated by precipitation.

(51 In the MgO neutralization (two-stage) step, MgO is added to the filtrate from the MgO neutralization (-stage) step, and the pH is adjusted to 8.7.
9.3, and the valuable metal components remaining in the liquid are recovered as hydroxide precipitate and returned to the leaching process (second stage). A portion is separated and stored outside the system. The filtrate at this time is magnesium sulfate and can be dumped into the ocean.

The biggest reason for two-stage neutralization with MgO is Ni.

It suppresses the loss of valuable metals such as Co and Cu to the waste liquid, and also minimizes the mixing of MgO into the hydroxide precipitate in the first stage.
) *Implemented to reduce CO3 consumption.

(6) In the ammonia dissolution step, MgO neutralization (
20 to 100 g/j of Ni-containing, Co, and Cu hydroxide precipitates obtained in Step 1)! of ammonia water and 50-150
Ni dissolved in a solution containing g/l (NHn)zcO3
, to obtain a Co and Cu ammonium complex salt. On the other hand, Mg and Mn mixed into the hydroxide precipitation are precipitated and separated as magnesium carbonate and manganese carbonate. This precipitate is returned to the leaching process (stage 2). Also, some of it is separated and stored outside the system.

(7) In the ammonia recovery and basic carbonate recovery steps, steam is blown into the ammonium complex salt containing Ni, Co and Cu to recover ammonia and at the same time obtain a mixed basic carbonate of Ni, Co and Cu. The recovered aqueous ammonia is circulated for dissolving hydroxide precipitates.

Although various conventional methods can be considered for the subsequent steps, for example, they are carried out by the following method.

(8) In the step of dissolving basic carbonate in sulfuric acid, Ni,
A basic carbonate containing Co and Cu is dissolved using a new sulfuric acid or Cu removal electrolytic process to obtain a mixed solution of nickel sulfate, cobalt sulfate, and copper sulfate.

(9) In the Cu-removal electrolytic step, in order to separate only the Ca component, electrolysis is performed at a low voltage of 0.5 to 1.5 V to obtain electrolytic Ca powder. At this time, a PtTi-containing electrode is used as the anode material, and a C plate is used as the cathode material. This electrolytic Ca powder has a purity of 99.
It is a high purity product of 9%.

On the other hand, since free sulfuric acid is generated in the solution after electrolysis, it is circulated and used for dissolving basic carbonates.

QO) In the solvent extraction and electrowinning process of Co,
After adjusting the pH of the Cu-removed solution with aqueous ammonia, solvent extraction is carried out with a phosphoric acid-based organic solvent such as PC88A or D21EHPA, followed by stripping of the Co electrolyte solution, and the resulting cobalt sulfate solution is electrolyzed with G electrolysis.

get. The Co metal thus obtained has a high purity of 99.9% or more. A PB plate is used as the anode material during Co electrolysis, and a stainless steel plate is used as the cathode material.

(11) In the Ni solvent extraction and electrowinning process, after adjusting the pH of the Cu-removed solution with aqueous ammonia, LIX64
Ni is extracted with an oxime-based organic solvent such as N, and then N
i Electrolytic solution stripping is carried out, and the obtained nickel sulfate solution is electrolyzed to obtain electrolytic Ni. Ni obtained in this way
The metal is a high purity product of 99.9% or more. During Ni electrolysis, a PB plate is used as the anode, and a stainless steel plate or Ni seed plate is used as the cathode.

In the ammonia and gypsum recovery process, Ni removal
In order to recover the ammonia content from the ammonium sulfate contained in the liquid, Ca (OR) 2 is added and heated with steam to recover ammonia water, which is then circulated to each pH adjustment process using ammonia. On the other hand, the transferred liquid after ammonia separation is separated by filtration to obtain gypsum and a filtrate that can be disposed of.

According to the present invention, high-purity Ni, Co
, it is possible to produce Cu.

On the other hand, Ni, Co, and Cu contained in the Co crust
The main metals other than Fe and Mn are separated into each leaching residue and/or Fe(OH)z and MnC0=. These are substances that are chemically stable and can be disposed of or stored without becoming a source of pollution.

(Example) Mn 14.6%, Fe8.40%, Co0.34%,
A Co crust with a composition of 0.34% Ni and 0.064 Cu was ground to 100 meshes or less, and a slurry concentration of 10 was prepared using sulfite water equivalent to twice the chemical equivalent of the amount required to dissolve the Mn in the Co crust. %, stage leaching for 10 minutes at a temperature of 18°C. Subsequently, enough Co crust was added to consume the sulfite content in the obtained leachate, and a second stage of leaching was carried out under the same conditions to obtain Fe2.5g/β, Mn13.
, Og/1, CuO,06g/l, Co0
．． 31g/12, Ni0.32g/12.

A leachate with a sulfite concentration of 60 g/l was obtained.

An amount of air equivalent to five times the chemical equivalent required to oxidize Fe"° ions in this leachate to Fe3+ ions and sulfite ions to sulfate ions was blown into the leachate for 4 hours.
2.5 g/l, Mn13.0g/l, C
u0.06g/l.

Co0.31g/l, Ni0.32g/l,
Sulfate ion 90g#! A ρ oxidation solution was obtained. The oxidation temperature at this time was 60°C or higher.

This oxidized solution was neutralized to pH 3.5 using Ca (OH) t at a temperature of 18°C, and then separated by filtration to obtain 13.0 g of Mn.
/ 12, CuO, 06g/j! , Co0.3
18/l, Ni0.32g/II, S04
A filtrate and Fe (OH) 3 precipitate of -0.03 g/l were obtained.

MgO was added to this iron removal solution at a temperature of 30°C to neutralize it in the first stage until the pH reached 8.2, and then it was filtered to remove Cu (OH).
zO89%, 'Co(Oil)z 4.9%, N
1(Otl)z4.6% precipitate and Co0.003
g/12, Ni0.03g/II, MgS
A filtrate of O434, Og/II was obtained.

The filtrate after MgO neutralization was adjusted to pH 9 using MgO at 30°C.
Perform the second stage of neutralization at 0, followed by filtration and Co(OH)zO
,005%, N1(OR)zl, 0%, Mg07.
A 1% precipitate was obtained. This precipitate is returned to the leaching (two-stage) step. - On the other hand, the component in the obtained filtrate is Mg5O
*54.0 g/1, and this liquid can be diluted and dumped into the ocean. Incidentally, a part of the precipitate is separated out of the system.

MgO neutralization (- stage) The precipitate was heated at a temperature of 30°C with free NH33
0g/A, (NH*)zco:tloog/l
The slurry was adjusted to a concentration of 10% with a solution of
CuO, 5g/12. NHd30g/CCO+”-1
0.6g/j! A liquid was obtained. On the other hand, MnCO3, Mg
The undissolved residue containing C0:+ as the main component is returned to the leaching (two-stage) step.

Also, some of it is separated and stored outside the system.

By blowing steam into this ammonia solution and heating it at 90°C or higher for 3 hours, 130g#! of ammonia water and Ni25.6%, Co25.6%, Cu4. ．．
A basic carbonate containing 7% was obtained. The ammonia water recovered at this time is circulated for dissolving Ni, Co, and Cu hydroxide precipitates. This basic carbonate of Ni, Co, and Cu was dissolved at a temperature of 18°C for 1 hour with sulfuric acid equivalent to the chemical equivalent required to dissolve Ni, Co, and Cu to form Ni27.
g/J.

A solution containing 27 g/l of Co and 5 g/l of Cu was obtained.

A mixed solution containing Ni, Co and Cu was electrolyzed under the following conditions to obtain electrolytic Ca powder with a purity of 99.9%.

Cu electrolysis conditions: Anode material Ti electrode Electrolyte Ni 27g
/ 1 Cathode material C plate Co27g / 1 Voltage 1. OV Cu 5g/1 Current density 300A/m” Electrolysis temperature 50°C pH 1.0 Liquid composition after removing Cu: Ni27g/l, Co27g/
CCu0.001 gel.

The pH of the Ni- and Co-containing sulfuric acid solution after removing Cu was adjusted with ammonia and then extracted with a solvent to obtain a Co-free solution. Further, the Go-containing organic solvent was stripped with a Co electrolyte solution to obtain a Co electrolyte solution, and then electrowinning was performed to obtain electrolytic CO with a purity of 99.9%.

The solvent extraction conditions and electrolytic conditions for Co at this time are shown below.

Goo medium extraction conditions: Extractant PC88A diluent N-paraffin stripping solution Co electrolyte solution H adjustment NH4011 Extraction pH 5.5 Back extraction pH 3.3 Temperature 60°C Co electrolysis conditions: Co solution concentration 75g/Il electrolysis temperature 60°C Current density 200A/m” Anode PB plate Cathode Stainless steel plate The Ni-containing sulfuric acid solution after removing Co was adjusted to pH 3F with ammonia, then solvent extracted to obtain a CO-free solution, and the Ni-containing organic solvent was added to the Ni-containing organic solvent.
The electrolytic solution was stripped to obtain a Ni electrolytic solution, and then electrowinning was performed to obtain electrolytic Ni with a purity of 99.9%. The solvent extraction conditions and electrolytic conditions for Ni at this time are shown below.

Solvent extraction conditions for Ni: Extractant LIX64N diluent N-paraffin stripping solution Ni electrolyte solution H adjustment NH4OH Extraction pH 8.0 Reverse extraction p) I 2.5 Ni electrolysis conditions: Ni solution concentration 75 g/1 current Density 200A/m" Ano-F PB plate cathode Stainless steel plate 1
30g/j2 of ammonia water and the residual liquid after ammonia separation were separated by filtration to obtain gypsum. At this time, the recovered ammonia water is circulated to the Co and Ni solvent extraction step.

(Effects of the Invention) As described above, according to the method of the present invention, N
i. Valuable metals such as Co and Cu can be recovered with high purity and easily, and other metals can be separated in a form that is chemically stable and does not become a pollution source, and waste acid can be stored. It is.

[Brief explanation of the drawing]

FIG. 1 shows an example of a flow sheet for the method of the present invention.

Claims (1)

[Claims] The first leaching process involves leaching the Co crust with sulfite water in excess of the chemical equivalent required to dissolve the Mn content in the Co crust, followed by the leaching process in which the excess sulfite content in the first leaching solution is consumed. A second leaching step in which Co crust is added and leached; a step in which Fe contained in the leachate thus obtained is oxidized into ferric salts and sulfite into sulfates; and this solution is oxidized with Ca(OH). )_2 to separate Fe and obtain an iron removal solution, the first MgO neutralization step to add MgO to the iron removal solution to increase the pH and obtain Ni, Co, and Cu hydroxides, the first MgO The filtrate from the neutralization step is further enriched with M.
Ni, Co,
A second MgO neutralization step to obtain Cu hydroxide, a step of dissolving the hydroxide obtained in the first MgO neutralization step with aqueous ammonia containing ammonium carbonate, and this Ni, Co
, a step of blowing steam into an ammonia solution of Cu to recover ammonia and at the same time obtaining basic carbonates of Ni, Co, and Cu; thereafter, processing by a conventional method to obtain Ni, Co, and C;
A method for smelting and refining Co crust, characterized by separating and recovering u.