RU2356836C1 - Method of complex treatment of serpentinite - Google Patents

Abstract

FIELD: chemistry; metallurgy.

SUBSTANCE: present invention pertains to metallurgy and chemistry of inorganic substances. According to the invention serpentinite is leached with hydrochloric acid. The suspension is filtered, obtaining magnesium chlorate solution and silicon dioxide. Impurities are removed from the magnesium chlorate solution through neutralisation, obtaining a nickel-iron concentrate. Carnallite is produced from the purified magnesium chlorate solution and spent electrolyte. The carnallite is dehydrated and subjected to electrolysis, obtaining magnesium, chlorine and spent electrolyte. The nickel-iron concentrate is leached by 10-15% hydrochloric acid at temperature 80°C and pH 3-5. The suspension is filtered, obtaining an iron-containing residue and a solution, containing nickel chloride. Nickel compounds are extracted from the solution containing nickel chloride by treatment with a solution of sodium hydroxide at pH=8.0-8.5. The residue is washed in water soluble salts-chlorides, dried and calcinated, obtaining a nickel concentrate.

EFFECT: increased concentration of nickel oxide in the nickel concentrate.

2 cl, 1 tbl, 1 ex

Description

The invention relates to the field of metallurgy and chemical technology of inorganic substances and can be used for complex processing of serpentinite to obtain marketable products: silicon dioxide, magnesium compounds - magnesium chloride and / or carnallite, metallic magnesium, iron and nickel-containing concentrates.

A known method of processing serpentinite / Pat. RF №2241670, IPC C01F 5/30, С25С 3/04, C01B 7/01; 33/14, 07/21/2007 /. Serpentinite is leached with hydrochloric acid, the pulp is separated by filtration into silica and a magnesium chloride solution. Silicon dioxide is chlorinated to give silicon tetrachloride, from which aerosil is isolated by vapor-phase hydrolysis. The chlorine-magnesium solution is purified from impurities by neutralization to obtain an iron-nickel concentrate. Carnallite is synthesized from a purified MgCl ₂ solution and spent electrolyte, which, after dehydration, is used for the electrolytic production of magnesium.

The disadvantages of this technology is the production of chloride waste containing FeCl ₃ , AlCl ₃ , CrCl ₃ , MgCl ₂ , MnCl ₂ , etc., formed during the chlorination of silicon dioxide. There are certain difficulties for the separation of a mixture of chlorides and to obtain individual compounds. In addition, when cleaning chlormagnesium solutions, the resulting iron-nickel concentrate in calcined form contains no more than 2.4% NiO, which complicates its processing to produce individual nickel compounds. With this purification, no separation of iron and nickel compounds occurs.

A known method of complex processing of serpentinite using sulfuric acid / Pat. RF №2097322, IPC C01B 33/142, C01F 5/02, C01D 5/02, 11.27.97 /. This method is not suitable for producing magnesium metal by electrolysis, for the production of which anhydrous magnesium chloride and / or carnallite compounds are used.

A known method of complex processing of serpentinite with obtaining pure silicon dioxide / Pat. RF №2243154, IPC CO1B 33/12, 02.25.2003 /. Serpentinite is leached with a hydrochloric acid solution containing 10-21% HCl at a temperature of 60-100 ° C and W: T = 3-10: 1 for 2-6 hours to obtain silicon dioxide and a chlorine-magnesium solution. The chlorine-magnesium solution is purified from impurities by neutralization in two stages: in the first, by brucite at 80-90 ° С and pH 3.5-4.0, in the second, by sodium hydroxide solution to pH 6-7 with the addition of sodium sulfide or hydrosulfide. The disadvantages of this method are the large losses of Nickel with sediment stage I purification, reaching 75-80%. The degree of precipitation of iron is ~ 80%. In the second stage, a concentrate is obtained containing 4.0-4.5% NiO and up to 75% Fe ₂ O ₃ . There is no separation of iron and nickel, due to the fact that hydroxide compounds of iron are a good collector for compounds of nickel.

The closest analogue is a method of complex processing of magnesium silicates / Pat. RF №2290457, IPC С25С 3/04, C01F 5/32, publ. 12/27/2006. Bull. No. 36 / is a prototype.

The essence of the method is as follows. Ground serpentinite is classified into classes and magnetically separated to remove calcium-containing minerals. The magnetic fraction is leached with hydrochloric acid. The resulting solution of magnesium chloride is separated from amorphous silica, which is washed and dried. The magnesium chloride solution is purified from impurities to obtain an iron-nickel concentrate. A purified solution of magnesium chloride and ground spent potassium electrolyte are used to produce synthetic carnallite, which is dehydrated and fed to the electrolysis. Electrolysis produces metallic magnesium, chlorine, and spent electrolyte. The electrolyte is used to synthesize carnallite. Chlorine is converted to hydrogen chloride, which is sent to dehydrate carnallite. Hydrogen chloride is isolated from the dehydration gases to produce hydrochloric acid, which is used to leach serpentinite. The disadvantage of this method is to obtain an iron-nickel concentrate with a low nickel oxide content (not more than 2.5% NiO).

The technical result of the proposed method is to increase the concentration of Nickel oxide in the processing of iron-nickel concentrate with obtaining Nickel concentrate.

The technical result is achieved as follows. The nickel-iron concentrate is additionally leached with hydrochloric acid. The resulting pulp is filtered to obtain an iron-containing precipitate and a solution containing nickel chloride. Nickel compounds are isolated from the solution by precipitation with a solution of sodium hydroxide or carbonate.

The essence of the proposed method lies in the following set of essential features.

“The ground serpentinite is leached with hydrochloric acid, the suspension is filtered to obtain a chlorine-magnesium solution and silicon dioxide. The chlorine-magnesium solution is purified from impurities by neutralization to obtain an iron-nickel concentrate, which is separated from the purified chlorine-magnesium solution. The synthesis of carnallite is carried out from purified chlorine-magnesium solution and ground spent electrolyte. The resulting carnallite is dehydrated and subjected to electrolysis to obtain magnesium metal, chlorine and spent electrolyte. The electrolyte is used to synthesize carnallite. Chlorine is converted to hydrogen chloride, which is used to dehydrate carnallite. Hydrogen chloride is isolated from the dehydration gases to produce hydrochloric acid, which is used to leach serpentinite. The iron-nickel concentrate obtained at the stage of purification of the chloromagnesium solution from impurities is leached with 10-15% acid at a temperature of 80 ° C to pH 3-5, the suspension is filtered to obtain an iron-containing precipitate and a solution containing nickel chloride. Nickel compounds are isolated from a solution containing nickel chloride by treatment with a solution of sodium hydroxide at pH 8.0-8.5, the precipitate is washed from water-soluble salts of chlorides, dried and calcined to obtain a nickel concentrate.

Based on the studies, it was found that when using hydrochloric acid with a concentration of less than 10%, solutions with a low nickel content are formed, and more than 15% increases the degree of transition of iron into solution. At temperatures less than 80 ° C, a low speed of the process is observed, its duration increases, which leads to unjustified costs. At pH less than 2, the degree of transition of iron into solution increases, and at pH> 5, the leaching process practically stops.

When nickel is precipitated from a solution at pH <8, incomplete precipitation of nickel occurs. It is known that the onset of nickel deposition from a 1M solution is 6.7, and the pH of complete nickel deposition is 9.5. Moreover, the residual nickel concentration is less than 10 ^-5 M / Lurie Yu.Yu. Handbook of analytical chemistry. M .: Chemistry, 1971. P.248 /.

An example implementation of the method.

100 g of iron-nickel concentrate composition, wt.%: 10.4 Fe; 0.29 Ni; 0.15 Mn; 0.25 Cr; 2.4 SiO ₂ ; 11.0 Mg; 0.68 Ca; 46.3 H ₂ O; 61.2 p.p.p .; Ni / Fe ratio = 0.028, mixed with 150 ml of water, the pulp was heated to 80 ° C and the supply of hydrochloric acid (1: 1) to a certain pH value was started. Table 1 shows the effect of pH on the degree of transition of iron and nickel compounds into the solution.

As follows from the obtained data, the leaching pH affects the degree of transition of iron and nickel into solution, as well as the degree of purification of nickel from iron. At pH <3.0 and> 4.5, the degree of extraction of iron into the solution increases, the degree of purification of nickel from iron is 37 at pH 3.0 and 196 at pH 4.5.

At a pH of 3.5–4.25, the degree of nickel recovery is 54–70%, and iron practically does not go into solution. The degree of separation of nickel and iron is ~ 76000-185000.

Nickel hydroxide was precipitated from a solution containing nickel chlorides by treating it with a 2N NaOH solution to a pH of 8.0-8.5. In this case, the degree of nickel deposition was 99.50-99.97%. The wet cake (60-68% H ₂ O; pp 80-82%) contained up to 4.8-4.9% Ni or 6.1-6.2% NiO. In the dried at 100 ± 5 ° C, the nickel content increased to 14.9%, and in the calcined at 700 ° C to 25%.

Thus, the developed technology allows separating iron and nickel to obtain iron and nickel-containing concentrates, as well as returning magnesium chloride to the production of magnesium metal.

Table 1 The effect of pH on the degree of extraction of iron and nickel in solution HCl consumption (1: 1), ml pH Filtrate analysis The degree of extraction,% The degree of purification of Ni from Fe * volume ml concentration, g / dm ³ Ni / Fe ratio Ni Fe Ni Fe 1.85 3.0 381 0.80 0.77 1,039 one hundred 2.82 37 190 3.8 386 0.52 0.0001 5200 69.2 0,0003 185714 173 4.0 369 0.42 0.0001 4200 53.5 0,0003 150,000 170 4.25 366 0.43 0,0002 2150 54.3 0,0007 76786 160 4,5 356 0.66 0.12 5.5 81.1 0.36 196 * The degree of purification of nickel from iron was calculated as the ratio of nickel to iron in the final solution to such a ratio in iron-nickel concentrate.

Claims (2)

1. A method for the complex processing of serpentinite, including its leaching with hydrochloric acid, filtering the suspension to obtain a magnesium chloride solution and silicon dioxide, neutralizing the magnesium chloride solution from impurities to obtain an iron-nickel concentrate, carnallite synthesis from purified magnesium chloride solution and spent electrolyte, carnallite dehydration and its obtaining magnesium, chlorine and spent electrolyte returned to the process, characterized in that the iron-nickel concentrate in schelachivayut 10-15% hydrochloric acid at a temperature of 80 ° C to pH 3-5, the suspension was filtered to give the iron-containing precipitate and a solution containing nickel chloride. 2. The method according to claim 1, characterized in that nickel compounds are isolated from a solution containing nickel chloride by treatment with a sodium hydroxide solution at pH 8.0-8.5, the precipitate is washed from water-soluble salts of chlorides, dried and calcined to obtain nickel concentrate.