Summary of recovery of manganese from tungsten slag treatment

1. Manganese and manganese compounds

(1) The nature of manganese and its use [1]

After the second half of the 18th century, the Swedish chemist TO Bergmann and assistants from Gan Ying studied Pyrolusite, and successfully isolated the metal manganese. Metal manganese is hard and brittle, silvery white, density 7.20 g / cm3, melting point 1244 ° C, is a refractory metal, boiling point of 2097 ° C. The valence is +2, +3, +4, +6 and +7. Among them, the +2 valence (Mn 2+ compound), the +4 valence (manganese dioxide, which is a natural mineral), and the +7 valence (permanganate, such as KMnO 4 ), and the +6 valence (manganate, such as K 2 MnO 4 ) are Stable oxidation state. In the solid state, it exists in four allotropes, α-manganese (body-centered cubic), β-manganese (cube), γ-manganese (face-centered cubic), and δ-manganese (body-centered cubic). The ionization energy is 7.435 eV. It is easily oxidized in the air to form a brown oxide coating. It is also easy to oxidize at elevated temperatures. A layered rust scale is formed upon oxidation, the oxide layer closest to the metal is MnO, and the outermost layer is Mn 3 O 4 .

Metal manganese is chemically active and soluble in acid. Manganese is an indispensable steelmaking raw material, 90% to 95% manganese are used in the metallurgical industry, mainly as a deoxidizing and alloying agent, typically manganese ore is iron-manganese alloy added Tempered steel. There are many types of manganese-containing steels, and manganese steel with a hardness of 15% has high hardness and high strength, and can be used to manufacture pulverizers, ball mills and rails. The remaining 10% to 5% of manganese is used in other industrial fields, such as the chemical industry (manufacturing various manganese-containing salts), light industry (for batteries, matches, paints, soaps, etc.), building materials industry (glass and ceramics). Colorants and fading agents), the defense industry, the electronics industry, as well as environmental protection and farming, and so on. In short, manganese has a very important strategic position in the national economy.

In addition, manganese is also the metal element most closely related to psychiatry. It has important physiological functions such as promoting bone growth and development, protecting the integrity of fine granules in cells, and maintaining normal brain function. When manganese deficiency, it can affect reproductive ability. It is possible to cause congenital malformations of the offspring, abnormal formation of bone and cartilage, impaired glucose tolerance, and can also cause neurasthenia syndrome, affecting mental development.

It can be seen that manganese plays an important role in both industrial production and the survival and development of living organisms.

(2) Main compounds of manganese and their properties and uses

The valence of manganese is +2, +3, +4, +6 and +7, so manganese has various valence oxides and manganese salts. Common manganese compounds are manganese dioxide, trimanganese tetraoxide, manganese chloride, manganese sulfate, and high. Potassium manganate and the like. Its nature and main uses are as follows:

1. Manganese dioxide (MnO 2 )

The skeleton structure of manganese dioxide is [MnO 6 ] octahedron, the oxygen atom is on the octahedral corner, and the manganese atom is in the octahedron, which is an amphoteric oxide. It is a very stable black or brown powdery solid at room temperature. It is the main component of pyrolusite, and its density of 5.0g/cm 3 is insoluble in water. It is the most important manganese oxide. Manganese oxide dust can cause human manganese pneumoconiosis.

In the case of a reducing agent, it exhibits oxidative properties. For example, manganese dioxide is placed in a hydrogen stream and heated to 1400 K to obtain manganese oxide; manganese dioxide is heated in an ammonia gas stream to obtain brown-black dimanganese trioxide; and manganese dioxide is reacted with concentrated hydrochloric acid to obtain dichloroethylene. Manganese and chlorine.

In the case of strong oxidants, it also appears to be reducing. For example, manganese dioxide, potassium carbonate and potassium nitrate or potassium chlorate are mixed and melted to obtain a dark green melt, and the melt is dissolved in water to obtain a compound of potassium pentoxide, potassium manganate. It is a strong oxidant in acid medium.

It is widely used in steelmaking, and in the glass manufacturing industry, a small amount of manganese dioxide is added as a decolorizing agent (the ferrous salt is oxidized to a trivalent iron salt to fade). In addition, manganese dioxide can also be used as a combustion improver in the match industry. The oxidizer and depolarizer of the battery industry, the drier of paint and ink, and potassium hydroxide can be mixed into potassium permanganate (KMnO 4 ).

In the laboratory, its oxidizing property is often used, and mixed with concentrated hydrochloric acid (HCl) to prepare chlorine gas (Cl 2 ):

MnO 2 + 4HCl (concentrated) = MnCl 2 + Cl 2 ↑ + 2H 2 O

2. Trimanganese tetraoxide (Mn 3 O 4 )

Brownish black powder, density 4.856, melting point 1705 ° C, insoluble in water, partially soluble in sulfuric acid and hydrochloric acid. The electronics industry production of manganese zinc ferrite soft magnetic material is an important raw material. It is mixed with ferric oxide and zinc oxide in a certain ratio, and then molded and sintered to form a high-performance magnetic conductive material-soft ferrite. The magnetically permeable material has a narrow residual magnetic induction curve and can be repeatedly magnetized. And its DC resistivity is high, which can avoid eddy current loss. Therefore, it can be manufactured in high-quality inductors, TV flyback transformers, telephone transformers, magnetic amplifiers, antenna rods, etc., and can also be used to manufacture magnetic cores, magnetic disks, magnetic tapes, magnetic heads, and the like for storing information on a computer.

3. Manganese chloride (MnCl 2 )

Manganese chloride is also known as manganese chloride; manganese chloride; manganese chloride tetrahydrate and the like. According to whether or not it contains crystal water, manganese chloride can be divided into: anhydrous manganese chloride and aqueous manganese chloride, and according to the number of crystal water, it can be divided into: manganese chloride monohydrate, manganese chloride dihydrate, tetrachloride water Manganese, manganese chloride pentahydrate, etc. The most common are anhydrous manganese chloride and manganese chloride tetrahydrate and manganese chloride monohydrate. At present, anhydrous manganese chloride can be further classified according to its appearance shape: granular or spherical anhydrous manganese chloride and powdered anhydrous manganese chloride.

Rose monoclinic crystal, relative density 2.01, melting point 58 ° C, boiling point: 119 ° C, soluble in water, soluble in alcohol, insoluble in ether. It is water-absorbing and deliquescent. It loses one molecule of crystal water at 106 °C, and loses all crystal water at 198 °C to form an anhydrate. Suitable for pharmaceutical synthesis and feed adjuvants, analytical reagents, dyes and pigments. Magnesium alloy, aluminum alloy smelting, brown and dry tile production, and pharmaceutical manufacturing. It is also used as a trace element fertilizer in agriculture.

4. Manganese sulfate (MnSO 4 )

White or light pink monoclinic fine crystals. Soluble in water, insoluble in ethanol, heating to 200 °C or above, losing crystal water, losing most of the crystal water at about 280 °C, forming anhydrous salt melt at 700 °C, starting to decompose at 850 °C, releasing three due to different conditions Sulfur oxide, sulfur dioxide or oxygen.

In addition to being used as a feed additive, manganese sulfate is also an important basic manganese salt, such as electrolytic manganese metal used for smelting high-grade ferromanganese alloys and manganese- copper alloys; electrolytic or chemical manganese dioxide for high-grade batteries, and soft ferrite materials. High-purity manganese carbonate and trimanganese tetraoxide; also widely used in fertilizers, medicines, paint drier, paper making, ceramics, printing and dyeing, ore flotation, production of electrolytic manganese and other manganese salts.

Second, the status of manganese resources

(1) Characteristics of manganese mineral resources [2]

1. Resource Overview

The onshore manganese (metal) reserves are about 17 × 10 3 t, and the potential reserves of seabed manganese are about 163 × 10 3 t. Most of the world's manganese ore is concentrated in South Africa, the former Soviet Union, Australia, Gabon, Brazil, and India. The manganese mines in South Africa are concentrated in the Kuruman area of ​​Cape Province, and the metallogenic age is Cambrian. Three-quarters of the former Soviet Union was distributed in the Nikopol Basin in Ukraine and the Chiatura Basin (Georgia Republic) in the Republic of Georgia. The metallogenic age was early Tertiary.

China's manganese ore reserves account for about 6% of the world, manganese ore reserves economically recoverable reserves of 130 million tons, with an average grade of 22%. At present, 34.5 kg of finished manganese ore is required to produce 1 ton of steel. The domestic finished manganese ore grade is above 30%, and about 2 tons of raw ore produces 1 ton of finished ore. It is predicted that China will produce 3.5 million to 4.5 million tons of finished manganese ore per year from 2005 to 2020, and the required manganese ore will be 7 million to 9 million tons. The proven economically recoverable reserves can be continuously mined for 10 to 15 years. Domestic manganese ore can be used. For the annual output of steel 100 million to 130 million tons, the domestic manganese ore output guarantee in 2005-2020 is about 45%.

2. Behavior of manganese in geological action

Manganese is contained in the earth's crust at a content of about 0.1%. It is one of the iron group elements. In the magma action, the ferrous iron in the iron-magnesium mineral is often replaced. Most of the manganese nodules in the ocean grow around the seafloor debris, often Ba-Mg-Mn Ore. The manganese carbonates in sediments can be changed into low-grade rhodochrosite, manganese ore and manganite by metamorphism.

3. Industrial minerals and ore types of manganese

There are about 150 kinds of manganese-containing minerals, but mainly pyrolusite, hard manganese ore (Psilomelane, mMnO·MnO 2 ·nH 2 O), Manganesesite (MnO), Manganite (Mngan 2 ,Mn) OH) 2 ] and so on. Manganese ore is divided into metallurgical ore and chemical ore according to industrial use. The latter is mainly used to manufacture dry batteries. The former is divided into three levels according to the ratio of ferromanganese:

 Manganese ore Mn/Fe≧6～7, Mn=15～30%;

ï‚‚ Iron ore ore Mn/Fe 1, Mn + Fe > 30%;

 Manganese-bearing iron ore Mn=4～10%.

(II) Research status of secondary resource recovery of manganese

As is known to all, manganese ore is a non-renewable resource. The contradiction of short-term demand for manganese resources in China is also intensifying. It relies on the progress of mining and smelting technology and improves the management level of mining enterprises, strengthens the research on comprehensive utilization of resources, adheres to comprehensive mining and comprehensive utilization, and reduces costs. At the same time that the use of ore is converted into an economically usable ore, the study of recovering manganese from secondary resources is also urgent. At present, the main recovery of manganese comes from used batteries and scrap alloys and various types of metallurgical waste. Here we mainly introduce methods for recovering manganese from used batteries and used alloys.

1. Research on recovery of manganese from used batteries

The waste dry battery consists of zinc, manganese powder (MnO 2 ), copper cap, carbon rod, ammonium chloride and other components. After use, some zinc and manganese powders in the battery become zinc chloride and manganese trioxide in the chemical reaction. Etc., but they are still present in waste batteries. According to China's production level, battery production consumes 250,000 tons of zinc, 240,000 tons of manganese, 4,500 tons of copper, 60 tons of mercury , and a considerable amount of zinc chloride, graphite , iron, etc. [3,4] , according to mass conservation According to the law, these substances are still present in waste batteries. “Throwing away” means throwing away 250,000 tons of zinc, 240,000 tons of manganese, 4500 tons of copper and other useful substances. 96% of China's waste dry batteries are mercury-containing zinc-manganese dry batteries and alkaline manganese dry batteries. The main components are heavy metals such as manganese, zinc and mercury. Therefore, the waste dry battery treatment process we have studied is generally directed to these two types of batteries. At present, the research on the recovery of manganese metal in batteries mainly includes:

Ma Yaqin, Long Jinming, Du Aihua and others from the School of Materials and Metallurgical Engineering of Kunming University of Science and Technology and the School of Materials and Architectural Engineering of Guizhou Normal University recovered zinc and manganese from waste batteries and electroplated and reused them. They used a mixed aqueous solution of sulfuric acid and sulfurous acid in a volume ratio of 10:1 to pickle the waste dry battery to obtain a mixed aqueous solution of zinc sulfate and manganese sulfate, and used the solution as a main raw material to prepare a plating solution for zinc-manganese alloy plating. . The bath composition and process conditions are 23.4 g/L Zn 2+ , 19.2 g/L Mn 2+ , 252.8 g/L Na 3 C 6 H 5 O 7 ·2H 2 O, 1 g/L polyethylene glycol 1.5 g / L of thiourea, 50 mg / L Na 2 S 2 O 3 , pH 4 ~ 5, temperature 20 ~ 30 ° C, cathode current density 1 ~ 6 A / dm 2 . A zinc-manganese alloy coating containing 4.07% to 15.8% of manganese was obtained, and the surface of the coating was flat, the crystal structure was fine, and the bonding force was good [5] .

The Electrochemical Research Laboratory of Shanghai Electric Power College and the Key Laboratory of Thermal Equipment Corrosion and Protection of the State Power Corporation have conducted in-depth research on the preparation of Mn-Zn ferrite primary leaching process for waste zinc-manganese batteries. The effect of leaching conditions on the leaching effect of the ZnZn ferrite magnetic material prepared by using the waste zinc-manganese battery in the primary leaching process was studied. The active components in the waste zinc-manganese battery were immersed in the mixed acid and combined with the addition of oxalic acid as the reducing agent. The effects of liquid-solid ratio, temperature and time on the leaching effect of the active components of the battery and the form transformation and distribution of mercury in the battery were investigated. The results show that: at 40 °C, the ratio of 3:1 by volume of HCl and HNO 3 is mixed with acid at a liquid-solid ratio of 4:6, oxalic acid is added and the amount is controlled to be 120% of the theoretical amount, and the leaching time is above 12h. Under the two-step dissolution method, good results can be obtained. The recovery rate of manganese, zinc, iron and nickel can reach 99% or even 100%, and the recovery rate of copper can reach more than 90%. Various forms of mercury in used batteries It is converted into Hg 2+ into the immersion liquid, and the recovery of mercury is well controlled.

2. Research status of recovery of manganese from waste residue [6]

Zhou Zhiming, Su Wenzheng, Li Kun et al. The process of preparing anhydrous manganese chloride from manganese-rich slag was studied. The process conditions of using manganese-rich slag as raw material and hydrochloric acid as leaching agent to prepare anhydrous manganese chloride were studied. Studies have shown that: using quantitative fractionation plus acid method, the concentration of hydrochloric acid is controlled to 2 mol / L, the amount of hydrochloric acid is 180% of the theoretical amount, and the leaching solution is immersed for 1 h at room temperature. The leaching solution is deoxidized to remove iron, hydrolyzed to remove silicon, aluminum, and sulfide. Except heavy metals, and then crystallized and dried, anhydrous manganese chloride can be obtained, wherein the mass fraction of manganese chloride is 98.1%, and the total yield of manganese is 79.3%.

3. Research status of recovery of manganese from waste liquid [7]

The separation and recovery of manganese from wastewater by liquid membrane method and its separation mechanism. Potassium permanganate is a widely used inorganic strong oxidant. It is mainly used in the treatment of medicine, chemical industry, petroleum , mining and domestic water and sewage. Potassium permanganate is often discharged in the form of waste liquid, resulting in waste of resources. Nankai Institute xia, Liguo Jiang et al N7301 employed as carrier, Span-80 is a surfactant, a film kerosene solvent, sulfuric acid as the emulsion liquid membrane phase reagent within the recovered wastewater MnO4-. The migration mechanism was studied and the optimal operating conditions such as lactation and separation were determined. The structure shows that for the low concentration of manganese-containing wastewater of 7-125mg/L, the one-time separation can be reduced to less than 0.1mg/L, and the recovery rate of manganese is 99.8%.

4. Research status of recovery of manganese from waste alloys

Recovery of manganese from manganese furnace and manganese-iron alloy waste in electric furnace is a method for recovering manganese from manganese furnace and manganese-iron alloy waste in electric furnace Slurry; using a shaker to classify the slurry into different beds according to different specific gravity, the waste granules with the largest specific gravity are manganese slag, and the slag particles with smaller specific gravity than manganese slag are medium slag, and the slag is re-crushed and repeatedly washed. Manganese slag is produced; the slag particles with the smallest specific gravity are tail slag and are discarded. For the above-mentioned waste residue containing more than 10% of manganese, the manganese in the waste residue can be recovered by this method.

Third, the use of trimanganese tetraoxide and its preparation method

(1) Properties and uses of trimanganese tetraoxide [8,9]

In nature, trimanganese tetraoxide (Mn 3 O 4 ), also known as black manganese ore. The molecular weight is 228.81, and the theoretical manganese content is 72.03%. The ionic structure is Mn 2+ [Mn 2 3+ ]O 4 , tetragonal, black. The density is 4.7 to 4.9 g/cm3, the hardness is 5, and the natural black manganese ore streak is light red or brown.

Any other manganese oxide can be burned in air to obtain a brownish red Mn 3 O 4 powder. For example, when MnO 2 is heated to 950 ° C in air, Mn 3 O 4 is formed :

3MnO 2 Mn 3 O 4 +O2

MnO 2 and CO 2 act to form Mn 3 O 4 :

3MnO 2 +CO 2 Mn 3 O 4 +CO

After the manganese dichloride is heated at its melting point temperature, it is cooled to form Mn 3 O 4 :

3MnCl + O 2 Mn 3 O 4 +3Cl

γ-Mn 3 O 4 can be obtained by preparing high-purity manganese dioxide by liquid phase decomposition of manganese nitrate and then performing high-temperature baking.

Mn 3 O 4 can be reduced to aluminum by aluminum; it can be oxidized by oxygen to manganate in sodium carbonate melt:

3Mn 3 O 4 +8A1=9Mn+4A1 2 0 3 ,

2Mn 3 O 4 +5O 2 +6Na 2 CO 3 =6Na 2 MnO 4 +6CO 2

Mn 3 O 4 can be oxidized to manganate in a strongly alkaline medium and can be reduced to manganese by carbon monoxide:

Mn 3 O 4 +4CO=3Mn+4CO 2

Mn 3 O 4 reacts with nitric acid to form manganese dioxide, and with sulfuric acid or hydrochloric acid, it releases oxygen or chlorine:

Mn 3 O 4 +4HNO 3 =2Mn(NO 3 ) 2 +MnO 2 +2H 2 O

2Mn 3 O 4 +6H 2 SO4 (concentrated) = 6MnSO 4 +O 2 + 6H 2 O

Mn 3 O 4 +8KC1 (concentration) = 3MnC1 2 + C1 2 + 4H 2 O

When treated with boiling dilute nitric acid or dilute sulfuric acid, Mn 3 O 4 can only dissolve 2/3. Any other manganese oxide is burned in air to about 1000 ° C to obtain a brownish red Mn 3 O 4 powder.

(2) Use of trimanganese tetraoxide [10,11,12]

Mn 3 O 4 is mainly used to produce soft ferrite. MnZn ferrite is a soft magnetic material widely used in communication, audio-visual equipment, switching power supply and magnetic head industry, mainly composed of manganese, zinc and iron oxides. It is prepared by sintering in a certain ratio and then sintering.

Ferrite is a compound of Fe 2 O 3 and a divalent metal oxide. It is a novel non-metallic material in which manganese zinc ferrite is mainly composed of MnO, ZnO and FeO. Due to the special properties of ferrite, it has a wide range of uses in the electronics industry. For example, magnetic cores, magnetic disks and magnetic tapes used to store information in electronic computers, telephone transformers and high-quality inductors, television flyback transformers, magnetic recording heads, inductors, magnetic amplifiers, saturating inductors, antenna rods, etc. It is made of soft ferrite.

At present, the production of ferrite in China is mostly made of high-purity MnCO 3 as raw material. Because of the low manganese content of MnCO 3 , the loss of ignition is large, and a large amount of CO 2 gas is generated during heating and decomposition. The production process is difficult to control and is fired. The soft magnetic components are prone to microcracks and affect the quality of the product. Foreign countries have used a large number of high-quality magnetic components with a large surface and good activity of Mn 3 O 4 . Most of the foreign countries have adopted high-purity Mn 3 O 4 to produce high-quality soft magnetic components, which overcomes the defects when using manganese carbonate as raw material. Only a small number of similar components are produced in China. The main reason for this situation is the existence of Mn 3 O 4 production in China. Some technical problems, Mn 3 O 4 mainly depends on imports.

Mn 3 O 4 can also be used as a colorant for certain paints or coatings. Paints or coatings containing Mn 3 O 4 are sprayed on steel to exhibit better resistance than paints or coatings containing TiO 2 or Fe 2 O 3 . Corrosion performance. When necessary, Mn 3 O 4 or natural manganite may be used as a raw material for preparing other manganese oxides, manganese salts, manganese compounds and the like.

(III) Preparation method of trimanganese tetraoxide [13,14]

With the rapid development of the electronics industry, higher requirements have been placed on the quality of soft ferrites. Most of the foreign countries use high-purity manganese dioxide or trimanganese tetraoxide to produce high-quality magnetic components, and domestically, there are small quantities of similar components. Therefore, in order to support the advanced production lines introduced from abroad and ensure the quality of high-quality zinc-manganese ferrite products, research and development and production of high-purity Mn 3 O 4 has become a top priority in the soft magnetic industry.

There are a variety of methods for the preparation of Mn 3 O 4 . From the principle of preparation, it can be basically divided into two categories: one is oxidation of low-priced manganese, and the other is reduction of high-priced manganese; It is a metal manganese method, a high-priced manganese oxide method, a manganese carbonate method, a manganese salt method, and the like.

The following will introduce the raw materials required for preparation:

1. High-priced manganese oxide method (MnOx, x > 1.33)

The high-priced manganese oxide method can be subdivided into four methods:

1 Reduction of high-priced manganese oxides with excess methane gas

MnOx + CH 4 Mn 3 O 4 + CO 2 + H 2 O

The reduction temperature is different depending on the value of x, and the temperature is preferably controlled below 500 ° C to prevent further reduction of Mn 3 O 4 to MnO.

2 High-purity α-MnO 2 is decomposed into γ-Mn 3 O 4 when calcined above 950 ° C by heating high-purity α-MnO 2 to 1000 ° C in a boiling furnace for 1 h and then cooling.

3 Roast the EMD and remove it with H 2 SO 4

The method is to place the EMD in a porcelain crucible and heat it to 1100 ° C for 90 min, then cool it, then grind the product through a 180 mesh (0.083 mm) sieve, then 0.1 to 0.3 mol / L H 2 SO 4 Wash 3 times at 40 ~ 50 ° C, then rinse with distilled water to pH = 6 ~ 7, and dry at 105 ° C temperature.

4 EMD Raymond grinding semi-finished products plus HNO 3 method

This method is proposed on the basis of the method (3), the purpose of which is to avoid the Mn 3 O 4 cooling back to oxygen after high temperature roasting and disproportionation reaction during pickling, the specific method is as follows:

The EMD Raymond grinding semi-finished product is placed in a porcelain crucible, and calcined at 1050 ° C for 50-130 min., using tempering in the furnace, rapid cooling outside the furnace cover or rapid cooling outside the furnace, the prepared Mn 3 O 4 It is not allowed to re-mill the sample, wash it with HNO 3 and then dry it, then bake it at high temperature (955～1170°C for 10 min), then seal the outside of the furnace (or vacuum) and get cold. Get qualified Mn 3 O 4 products.

2, manganese carbonate method

Manganese carbonate prepared by the carbamate method (prepared by decomposing manganese ammonium carbamate complex at 79 ° C) is calcined in air at 1000 ° C to obtain high-density, high-purity Mn 3 O 4 for ferrite. The bulk density and tapping density of the product are 1.95 and 2.55, respectively, which is higher than the density of Mn 3 O 4 obtained by electrolytic MnO 2 , due to the degree of shrinkage of the particles. The pure MnCO 3 was calcined and cooled at different temperatures (900-1200 ° C), and the manganese content of the product was determined. It was found that the manganese content increased with the increase of temperature, and the suitable temperature for the formation of Mn 3 O 4 was 950-1050 ° C; It is finely ground and passed through a 180 mesh sieve, and then washed with 0.1 to 0.3 M of H 2 SO 4 . The product contains 71.42% of manganese, and the impurity content basically meets the requirements of electronic grade products. The manganese carbonate and HNO 3 are dissolved at pH=0.5-1.0, and the manganese nitrate solution obtained by the reaction reacts with 20% NH 3 ·H 2 O at pH=7.5-8 to form manganese hydroxide, and then at 600-650 ° C. The hydroxide is calcined, and the obtained Mn 3 O 4 is used to produce ferrite. For example, a manganese carbonate suspension (S:L = 1:3) is dissolved in 55% HNO 3 and filtered, and the manganese nitrate filtrate and 20% NH 3 ·H 2 O are treated to obtain a manganese hydroxide, which is washed by filtration. Thereafter, the hydroxide contained 0.01% of impurities, and after drying, it was baked at 600 to 650 ° C for 4 hours to obtain a Mn 3 O 4 product.

3. Iron-manganese alloy method

When the low-carbon ferromanganese is produced by blowing high-carbon ferromanganese in a converter, the dust collected in the dust collecting system is an ultra-fine spherical particle with an average particle size of 0.1 to 3 μm, containing more than 90% of trimanganese tetraoxide, and containing manganese. More than 60%. For example, a 30 t high carbon ferromanganese alloy melt is poured into a pre-bottom converter, and calcium oxide is added, and then oxygen is blown through the upper lance at a flow rate of 20 m 3 /min, while carbon dioxide is blown through the inner and outer tubes of the tuyere, respectively. oxygen. The dust generated by the converter, the dust collected by the bag filter is the manganese trioxide powder, and the Fe-Mn alloy with an average particle size of 0.06um can also be prepared by a wet process such as acid dissolution, impurity removal, oxidation, etc. Take manganese oxide.

4. Manganese salt (or Mn 2+ ) method

1 The manganese salt solution is added to the 3% NH 4 OH solution to raise the pH of the Mn 2+ -containing solution to about 9.5. The precipitate is washed with manganese hydroxide and oxidatively dried. The product is Mn 3 O 4 , and the impurities are removed by appropriate methods. .

2 Suspension solution at a certain temperature (100 ~ 140 °C) and a certain pressure (2.81 ~ 4.92 kg / cm 2 ), with 10% NaOH treatment of mine wastewater (containing Mn 2+ 300 ~ 3000 g / t) generated Mn ( OH) 2 , using air or oxygen as an oxidant to prepare easily filtered Mn 3 O 4 , during which a suspension of Mn(OH) 2 can be stirred.

3 Adding MnSO 4 solution while blowing oxygen into the aqueous ammonia solution, the temperature of the aqueous ammonia solution is set between 40 and 80 ° C, and the ammonia concentration in the aqueous ammonia solution is 2 to 3 times the concentration of MnSO 4 in the MnSO 4 solution. In the above case, Mn 3 O 4 can be obtained.

4 Add MnO 2 to the MnSO 4 ·5H 2 O solution, add NaOH, and stir for 2 hours under vacuum. At this time, pH=9, the pH of the filtrate after filtration of this solution is 9, and the filtered solids are treated with distilled water. The mixture was washed for 20 minutes and repeated twice. The filtrate after filtration finally had a pH of 6.7 and the product was Mn 3 O 4 .

5 Mn (NO 3 ) 2 was mixed with ammonium persulfate, dissolved in cold water below 20 ° C, 28% aqueous ammonia was added, and the resulting precipitate was filtered for 5 min. The solution after separation and separation is heated and boiled for 30 minutes, the heating is stopped, the solution is allowed to stand, the precipitate to be precipitated is sedimented, the supernatant is decanted, washed twice with distilled water, filtered, and the filter cake is washed with distilled water until the filtrate is not acidic, After the filter cake was dried, it was calcined at a temperature of 1000 ° C to obtain a black crystallized product of Mn 3 O 4 .

5, metal manganese method

1 using NH 4 + salt and amino acid as catalyst at 50-70 ° C, Mn and H 2 O react under bubbling aeration for several hours to obtain high purity Mn 3 O 4 , the catalyst forms a complex with Mn, resulting in Mn 2+ The activity is reduced and the reaction rate is increased.

2 The high-purity manganese metal powder is added to the aqueous solution to form a suspension, and the oxygen-containing gas is continuously introduced and heated to 30 to 100 ° C for 1 to 4 hours to fully oxidize the manganese metal powder into the Mn 3 O 4 product, followed by filtration and drying.

3 metal Mn particles in a SO 4 2- or Cl - containing solution with or without aeration, by changing the oxidation conditions (oxygen, oxidation time, temperature or Cl) The concentration, the particle size of the Mn powder, gives Mn 3 O 4 , MnOOH, and a mixture thereof.

Although the method for producing the Mn 3 O 4 has a plurality of, but due to the required sources of raw materials in the manufacturing process, and the equipment produced by mass Mn 3 O 4 and the like problems, so that most of the methods for the experimental methods. In actual production, the current domestic production is based on electrolytic manganese metal powder as the main raw material, plus appropriate additives to control certain conditions and oxidize in water.

(IV) Market prospects for trimanganese tetraoxide [15,16]

The world's soft ferrite output increased from 110,000 tons in 1985 to 220,000 tons in 1997 and then increased to 300,000 tons in 2000. In 2005, the world's production of soft ferrites reached 500,000 tons, of which China and Southeast Asia has the fastest growth rate. In 1985, the output of soft ferrite in China was about 7000 tons, and it reached 50,000 tons in 1997, 60,000 tons in 2000, and 100,000 tons in 2005. The world market will maintain a growth rate of more than 10%, and China will also be 10%. The annual growth rate of around 15% is growing.

China's Mn 3 O 4 is mainly produced from manganese metal. The annual output is about 3,000 tons, which cannot meet the needs of the electronics industry. It needs to import electronic grade Mn 3 O 4 2000t every year. In 1996, the former Ministry of Electronics Industry had decided that by the end of 2000, it would be necessary to use Mn 3 O 4 instead of high-purity manganese carbonate to produce soft magnetic materials nationwide. This will increase the capacity of the domestic Mn 3 O 4 market by more than 10,000 tons. Therefore, the development prospect of high quality Mn 3 O 4 is very broad.

Fourth, the comprehensive recycling of tungsten slag

(1) Significance of comprehensive recycling of tungsten slag

With the development of the metallurgical industry, tungsten ore has been further exploited and utilized, and the number of high-quality tungsten concentrates has decreased. The current process of tungsten smelting is mainly alkaline leaching. Almost all tungsten alkali leaching slag contains a small amount of valuable metals such as Ta, Nb and Sc Mn Fe. The annual production of ammonium tungstate, tungsten and oxygen products in China consumes up to 420,000 tons of tungsten concentrate. The tungsten slag is about 190,000 tons. The total content of Ta 2 O 5 +Nb 2 O 5 in domestic tungsten slag (mass fraction, the same below) is 0.54 to 0.65%, the content of WO 3 is 4 to 7%, and the content of Mn is 17%. Sc 2 O 3 content of 0.02 ~ 0.04%, both have a large comprehensive recovery value. These tungsten slags containing a large amount of useful metals are discarded as waste, which wastes resources and pollutes the environment. Therefore, how to recycle these wastes economically and effectively is of great significance for protecting the environment and making full use of resources.

(II) Research status of recycling and utilization of valuable metals in tungsten slag

The current process of tungsten smelting in China is mainly alkaline leaching. The obtained tungsten slag is basically alkaline leaching residue, which contains various valuable metals such as Ta, Nb, W and Mn. At present, the world has conducted in-depth research on the recovery of metals in tungsten slag. The main research results are:

1. Study on enrichment and recovery of rhodium from tungsten slag by acid leaching and sodium alkali fusion method [19]

Tungsten residue with 5% hydrochloric acid leaching at 40 ℃ 30min, an amount 2.5 times the theoretical amount of hydrochloric acid, which can remove 72.1% 74.7% iron and manganese, in this case 92% recovery of tantalum, niobium, recovery rate 84.6 %. The obtained acid is leached to the slag for sodium alkali fusion. When the mass ratio of sodium alkali to leaching slag is 3:2, the reaction temperature is 800 ° C, and the reaction time is 60 min, the contents of Ta 2 O 5 and Nb 2 O 5 are respectively 0.48. % and 2.74% of the ruthenium-rich concentrates have a recovery rate of 83% and a recovery rate of 74.8%. The total recovery rates of lanthanum and cerium were 76.4% and 63.3%, respectively. Experiments show that tungsten slag can be effectively enriched and recovered by acid leaching and sodium alkali fusion treatment.

2. Study on recovery of hydrazine by soda roasting-water immersion and acid leaching method [20]

The dosage of soda is 6.0 times of the theoretical amount, the calcination temperature is 850-950 ° C, the calcination time is 50 min, the water immersion liquid-solid ratio is 6:1, the time is 90 min; the HCl concentration is 20% during acid cooking, and the leaching liquid-solid ratio is 6 :1, the time is 60min. According to the above conditions, the slag-rich slag containing Ta 2 O 5 +Nb 2 O 5 up to 15.89% (where ω(Ta 2 O 5 ) is 4.06%) can be obtained, and the ruthenium recovery rate is 79.46%. The process can not only improve the current tungsten metallurgy process in China, but also make full use of natural resources, obtain raw materials for direct application, and reduce environmental pollution caused by a large amount of tungsten residue.

3, Moscow Institute of Steel and Alloys米德维杰夫, who proposed two high-flow processing of tin, tungsten-containing tin slag or low tungsten raw material. The first process is based on the reduction of tin in the W-Sn intermediate to metal tin and tin-containing intermetallic compound, followed by low temperature chlorination to recover tin in the form of tin chloride, and the chlorinated residue is acid treated. After leaching out Mn, Fe, and Sc, the leaching solution is sent to extract Mn, Fe, and Sc, and the leaching slag can be recovered by hydrometallurgical method of Ta, Nb, and W. The iron alloy can also be smelted in an electric arc furnace. The second process is based on first treating the raw material containing WO 3 , SnO 2 , Mn, Fe, Sc, Ta, Nb with an acid to obtain an aqueous solution containing Mn, Fe, and Sc, and leaching the slag to obtain an ammonium tungstate solution by ammonia leaching. Ammonia leaching residue containing Ta, Nb, Sn, Si. An aqueous solution containing Mn, Fe, and Sc is recovered by an extraction method, and then a manganese salt or MnO 2 is recovered from the raffinate. The ammonium tungstate solution is sent to the production of ammonium paratungstate, and the ammonia leaching residue can be recovered by reduction smelting first, and then Ta and Nb are recovered.

Five, the removal of iron in solution

In hydrometallurgy, an acidic solution is commonly used to leach ore, and the medium iron of the mineral is present in the solution in the form of divalent or ferric iron. The presence of iron is a great hazard to subsequent processes such as electrodeposition and must be removed. Commonly used iron removal methods are jarosite method, goethite method, hematite method and solvent extraction to remove iron.

(1) Precipitation and iron removal method

1. Potassium sulphate method

The jarosite method is a method of iron removal after years of experimental research and development in Australia's electric zinc company in the 1960s. At the same time, the Norwegian zinc company and the Spanish Asturian zinc company have also developed this method. The jarosite method is a good method for removing iron, and has the advantages of good iron removal effect and good formation of iron slag. The method of ferrochrome has attracted great interest in hydrometallurgical zinc smelting and has been rapidly promoted and applied. Since then, it has expanded to the fields of wet smelting such as cobalt , nickel, copper and manganese.

Yellow iron sputum is pure yellow or light yellow crystal, hexagonal crystal, alum stone structure, a=0.721nm, c=1.703nm, Z=3. The formula of the yellow iron scorpion can usually be written as A 2 0·3Fe 2 0 3 ·4S0 3 ·6H 2 0 or AFe 3 (S0 4 ) 2 (OH) 6 , or A 2 [Fe 6 (S0 4 ) 4 (OH) 12 ], wherein A represents a monovalent cation, which may be K + , Na + , NH 4+ , or Rb + , Ag + , 1/2 Pb 2+ or the like. [twenty one]

According to Babcan (1971), which has been studied for the hydrolysis process of iron sulfate and potassium hydroxide solutions, the jarosite stability zone is between pH 1-3 and temperature between 20 °C and 200 °C. If the pH is too low, no precipitate will be present. The pH will be high and iron will be present in goethite (up to 100 ° C) and hematite (above 100 ° C). [22] To study the equilibrium of the Fe 2 0 3 —S0 3 —H 2 0 ternary system at certain temperatures, it is also possible to use the ternary diagram to see the stable region of the samarium.

The formation of shovel precipitates is mainly affected by temperature, pH and seed crystals.

1 Temperature At low temperatures, potassium strontium, sodium strontium, and ammonium strontium can also be formed in solution, but the rate of formation is rather slow. At 20 ° C, the pH is 0.82 to 1.72 of Fe 2 (SO 4 ) 3 —S0 3 —H In the 20 % solution, the precipitation of iron-potassium strontium takes four weeks to six months to form. The precipitation speed of other kinds of iron sputum is slower, and the temperature can be increased to accelerate the iron removal rate.

2pH The acidity of the solution has a lot of influence on the iron and iron. The pH value of the solution rises, and the iron removal rate and iron removal rate of the iron slag are increased. The results obtained by different researchers are consistent. In a solution at 100 ° C, iron precipitation from iron precipitation gives a balance relationship [Fe3+] / [H2S04] = 0.01.

The results of some researchers in the 3 seed crystals showed that the seed crystals of the iron sorghum had a significant effect on the iron removal rate of iron sputum in the solution, while others pointed out that the influence of the seed crystals was not significant, which may be due to the different sedimentation conditions they chose. Caused. In fact, the precipitation of iron shovel is a new phase formation process. The seed crystals, the purity of the reagents used, and the state of the vessel wall all have an effect on the precipitation of the shovel. However, it is worth noting that the experimental conditions of the selected sedimentation are different. There is a big difference in the size of the impact. In the solution of low temperature, high acid, low ferric ion and alkali ion concentration, the chemical reaction of iron sputum formation is very slow. In this case, the effect of seed crystal on the precipitation of shovel is not obvious.

2. Goethite method

The goethite method is also a method of iron removal successfully applied to hydrometallurgy. It is generally believed that the goethite-type iron-slag slag has a large crystal form and has a small amount of valence metal and is easy to be filtered. The goethite method is a method of iron removal developed and applied by the Belgian Laoshan Company's Barron Plant, which was industrialized in 1970. The outstanding advantage of the goethite method is that it is suitable for a variety of acidic medium leaching solutions. The iron removal operation can be carried out at normal pressure and lower temperature (70-100 ° C), and precipitated as α-FeOOH in the sulphate solution. The main one is β-FeOOH. The iron ore method can remove lead slag with good filtration performance without adding other alkali metal cations, and can separate lead , silver and indium slag. The amount of slag is less than that of the yellow iron slag method, and its iron content is also high. The disadvantage of goethite is that there are many anions and cations, which reduces the value of iron slag as a by-product. According to the equilibrium diagram of the Fe 2 0 3 —H 2 0 system, Fe 3+ will form goethite under the condition of very low Fe 3+ concentration, and precipitate with FeOOH. Oxidation reduction potential and pH are two important factors controlling the behavior of iron in aqueous solution. The oxidizing environment promotes the precipitation of iron, which reduces the dissolution of iron.酸性条件通常有利于铁溶解，碱性条件则促使铁沉淀。针铁矿为一种很稳定的晶体，其溶解反应的平衡常数很小。

湿法冶金中工业料液含铁为高价和低价铁的混合物。为使针铁矿沉淀过称顺利进行，必须预先降低Fe 3＋ ，使沉淀过程中Fe 3＋始终维持在1g/l以下。实现这一目标有两条途径，即还原-氧化法(VM法)和部分水解法(EZ法)。

a 还原-氧化法(VM法)

电锌厂一般采用闪锌矿精矿作还原剂，其反应为：

ZnS＋2Fe 3＋ ＝Zn 2＋ ＋2Fe 2＋ ＋S

ZnS是一种惰性很大的还原剂，为加快反应速度，生产上采用近于沸腾的温

度(95～100℃)，硫酸含量保持高于50g/l，以避免Fe 3＋水解，一般还原3--6h。ZnS还原是一个高温高酸的缓慢过程。国外ZnS还原一般单独有一还原工序，使工艺流程长，蒸汽耗量大，硫渣需要返回焙烧等缺点。

采用针铁矿法除铁，氧化除铁工序包括紧密相连的两个反应，即低铁的氧化和高铁的水解。针铁矿法氧化沉铁是基于下列反应：

2Fe 2＋ ＋1/20 2 ＋3H 2 0＝2FeOOH＋4H ＋

空气氧化低铁是通过溶解在溶液中的氧来实现的。因而提高氧的溶解度可提高反应速度。

b 部分水解法(EZ法)

与还原-氧化法不一样的是，部分水解法不是把Fe 3＋还原成Fe 2＋ ，反而是把溶液中少量的Fe 2＋氧化成Fe 3＋ ，再把含大量铁的弱酸浸出液以喷淋的方式洒入搅拌均匀的含铁低于1g/l,的低酸溶液中，弱酸浸出液在接触槽内底液(适合针铁矿产生的)的瞬间，在巨大的热力学推动下，以水解的形式析出针铁矿沉淀，可视为三价铁离子直接水解，反应式如下：

Fe 3＋ ＋2H 2 0＝FeOOH＋3H ＋

由上反应式可以看出，硫酸高铁水解产生酸，要是不用中和剂中和，产物必将发生变化，因此，要使反应槽内溶液保持在一定范围的pH，湿法炼锌过程一般用焙砂不断中和余酸。

3、赤铁矿法

赤铁矿有二种结晶形态，即γ-Fe 2 0 3和α-Fe 2 0 3 。天然赤铁矿在结构上属于α-Fe 2 0 3 ，它是顺磁性的，而γ-Fe 2 0 3则具有很强的铁磁性。γ-Fe 2 0 3的转变温度到400℃，加热到400℃时，它就会向α-Fe 2 0 3转变，同时磁性消失。加热从低温水溶液中析出的氢氧化铁时，首先得到的是针铁矿继而是水赤铁矿(α-Fe 2 0 3 ·0.5H 2 0)，而γ-Fe 2 0 3则是加热过程的第三级产物。针铁矿与γ-Fe 2 0 3的转变温度是160℃。如果采用高温水解法，可以得到过滤性能良好的赤铁矿。

从Fe 2 0 3 —S0 3 —H 2 0系在200℃高温下的等温线可以看出，在此温度下，Fe 2 0 3能大部分析出。

（二）溶剂萃取除铁

虽然已经对许多萃取剂作了大量研究，可工业上能用于溶剂萃取技术除铁的却还没有，主要是因为溶剂萃取铁在萃取率和反萃率上总是此消彼长。萃取率高往往反萃困难，反萃率高时又因萃取率低而用途不大。

如果能解决上述难题，溶剂萃取技术因可得到纯的铁化合物，将会是一种最有前景的除铁方法。

（三）各种除铁方法比较

黄铁矾法的主要优点是：

1、可获得适于电解的硫酸盐溶液，同时锌、 镉 、铜的回收率提高；

2、铁呈结晶状态除去，过滤和洗涤性能较好；

3、铅、银、金富集在二次渣中，适合做炼锌厂的配料会进一步处理；

4、常压过程易和现有的电解锌车间结合；

5、最重要的优点是能从循环的电解液中除掉硫酸根，维持硫酸根在系统中的平衡。

黄铁矾法的缺点是渣量大，硫酸消耗较多。按黄铁矾法处理锌渣的电锌厂，如锌精矿含铁量按8％计，年产100kt锌的工厂，每年渣量约为53kt，显然，渣量太大。

针铁矿法的要点是使溶液中三价铁离子浓度在沉淀过程中保持较低水平，如低于lg/L，老山公司巴伦厂使用的是还原氧化法，首先将溶液中的铁还原为三价，然后在三价铁离子水解的条件下将二价铁缓慢氧化成三价铁。该工艺效率较低；过滤的料液较大；动力消耗大；酸平衡难于掌握；酸、碱消耗较大，设备较为复杂。针铁矿法渣量较黄铁矾法低，对于炼锌，针铁矿法锌回收率与黄钾铁矾相同，但铜的回收率不如黄铁矾法高。针铁矿法流程中硫酸盐平衡问题未获得很好的解决，目前主要控制加入有生成不溶硫酸盐的原料(如铅)、排除硫酸锌溶液以及用石灰中和电解液等办法维持硫酸盐平衡。

赤铁矿法除铁最富有吸引力的是此法除铁铁渣量少，含铁高；但需要较高pH值，且能耗最高，蒸汽耗量约占全厂60％，所以使用该法除铁的单位不多。最后，三种除铁方法的操作条件比较列于表1-1，各种方法的沉淀渣的主要成份列于表1-2。

表1-1 黄铁矾法、针铁矿法、赤铁矿法操作条件比较


表1-2 不同方法沉淀渣的主要成分


六、本试验研究内容和意义

本研究主要是在目前现有的Mn 3 O 4制备方法研究的基础上，研究以钨渣为原料回收锰，用针铁矿法除铁获得纯锰化合物的方法。该法不仅可以降低产品成本，改善产品的质量，由于是以钨渣作为原料，还可以减少环境污染，节约能源。

(一)本次研究的主要内容

1、钨渣的酸浸

研究浸出剂硫酸浓度及用量对锰浸出率的影响，找出锰浸出率最高时的硫酸浓度和用量。

2、酸浸液除铁

浸出液中含有大量的铁离子，要得到比较纯净的锰化合物就必须将铁除到相当低的程度。研究了针铁矿除铁过程中pH值、温度及滴定速度对除铁率的影响，找出最优条件。

（二）本研究的主要意义      

近年来，国家工业部要在全国范围内实现用Mn 3 O 4代替高纯碳酸锰生产软磁材料，所以Mn 3 O 4需求量与日俱增。但作为锰锌铁氧体粉末主要原材料之一的四氧化三锰价格正不断上涨，价格上涨的主要原因是国内锰矿富矿基本开采完毕，资源供应量已经锐减，电解锰生产厂家的大量减产、关闭和一些刚性需求的释放，使市场现货供应量减少，导致电解锰价格上涨。因此，寻找其他的锰来源显得非常重要。

本研究以钨渣为原料制备高纯Mn 3 O 4 ，为新锰源的利用提供了重要的理论依据。

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