CN100448784C - Method for preparing trimanganese tetraoxide by direct oxidation of free bivalent manganese ion - Google Patents

Abstract

The invention is a method of preparing trimanganese tetroxide by directly oxidizing dissociative divalent Mn ions, belonging to metallic material field. And it uses purified solution of acid-dipped manganese ore solution--manganese sulfate or manganese chloride solution as raw material, uses ammonia as neutralizer, strictly controls pH value rising speed in the reacting course for preventing hydrolytic deposition of the divalent Mn ions as far as possible, uses oxygen or air as oxidant, and directly oxidizes the dissociative divalent Mn ions into trimanganese tetroxide on conditions of 30-95 deg.C and stirring. And it can effectively avoid producing large numbers of alkali manganese sulfates, thus able to largely reduce the sulfur content of the trimanganese tetroxide product, and in addition, largely reduce the contents of Ca and Mg impurities in the product by strictly controlling pH value in the reacting course.

Description

The free divalent manganesetion of a kind of direct oxidation prepares the method for trimanganese tetroxide

Technical field

The invention belongs to metal material field, the free divalent manganesetion of particularly a kind of direct oxidation prepares the method for trimanganese tetroxide.

Background technology

Mn ₃O ₄Be one of main raw material(s) of making soft magnetic ferrite, the trimanganese tetroxide that is used to prepare Mn-Zn ferrite requires very tight to foreign matter content.High-quality trimanganese tetroxide has vast market at home and abroad, and demand is also with the speed increase in every year about 15%.Trimanganese tetroxide is to begin to produce in 1997 in China, and development has formed and produced about 30,000 tons industrial scale per year rapidly at present, mainly satisfies the domestic market, and small part is used for foreign exchange earning.The trimanganese tetroxide production method mainly is that employing manganese powder oxidation style is the manganese powder catalytic oxidation at present both at home and abroad.Its technological process is: manganese powder after further being crushed to about 250 orders, is added deionized water by liquid-solid ratio about 6: 1, heat 30～80 ℃, add ammonium salt and make catalyzer, the blowing air oxidation can make trimanganese tetroxide.The factor that influences the product specific surface area mainly contains temperature of reaction, liquid-solid ratio, ammonium salt add-on and pH value in reaction etc.This technical maturity is simple, invest less, but cost height, specific surface area is less, is generally less than 10m ².g ^-1, foreign matter content is generally higher, the main source of impurity be bring into by starting material electrolytic metal manganese powder itself due to.The production of electrolytic metal manganese powder need be experienced complicated process procedure, be difficult to effectively avoid entering of some impurity in each link, thereby this method is difficult to fundamentally reduce the content of impurity in the trimanganese tetroxide.Production status at trimanganese tetroxide, various preparation methods have been studied both at home and abroad, be manganese salt directly prepares trimanganese tetroxide without electrolysis method wherein by the most promising method that everybody generally acknowledges, this method had been carried out broad research at home and abroad, the method that institute adopts all is to add alkali earlier with the mn ion hydrolytic precipitation, and then uses atmospheric oxidation.The problem that this method exists is that sulphur content residual in the product is very high; Next is that calcium, magnesium, silicon equal size are also seriously higher, carried out some researchs abroad at these problems, English Patent (GB1374975 wherein, 1974) in order to reduce that sulphur and calcium-magnesium content are taked once even enhancements such as double High Temperature High Pressure oxide treatment, but DeGrain, the sulphur content in the product are also up to 0.2-0.5% (SO ₃), apparently higher than 0.075% (SO of domestic existing enterprise standard ₃), calcium-magnesium content is also apparently higher than the prescribed value of existing standard.This also is to restrict the major cause that this method does not realize suitability for industrialized production always.

Summary of the invention

The present invention seeks in order directly the free mn ion in manganese sulfate solution or the manganese chloride solution to be oxidized to trimanganese tetroxide.Effectively avoid the generation of a large amount of alkali formula manganous sulfates, thereby reduce the sulphur content in the trimanganese tetroxide product significantly, reduce the content of calcium in the product, magnesium addition simultaneously significantly.

The present invention selects the scavenging solution of manganese ore pickling liquor for use, be that manganese sulfate solution or manganese chloride solution are raw material, make neutralizing agent with ammoniacal liquor, control the lift velocity of pH value of solution value in the whole oxidation reaction process, the lift velocity control of reaction process pH is according to pH and mn ion activity (α _Mn ²⁺) relational expression $\mathrm{pH}=\frac{1}{2}\lg k_{\mathrm{SP}}-\lg k_W-\frac{1}{2}\lg a_{{\mathrm{Mn}}^{2+}}$ (k in the formula _SPBe the solubility product constant of manganous hydroxide, k _wBe the ion-product constant of water) decision.The pH value of solution value can calculate the unhydrolyzed pH value of mn ion in the solution by this formula, as long as less than calculated value, then can be avoided the hydrolysis of mn ion.Avoid the divalent manganesetion hydrolytic precipitation by the lift velocity of control reaction process pH is manganous hydroxide and alkali formula manganous sulfate as far as possible.The pH of solution is controlled at 3～12 in the entire reaction course.

Make oxygenant with air or oxygen, the oxidizing reaction temperature scope is 30～95 ℃.Can directly be oxidized to high-purity even ultra-pure trimanganese tetroxide to the divalent manganesetion in the solution.

Present method cost is low, and sulfate radical and calcium in the trimanganese tetroxide product, Mg content are low.

Embodiment

Embodiment 1

With the 800ml manganese ion concentration is the reactor that the manganese chloride solution of 80g/L places 1500ml, is heated to 70 ℃, stirs, and drum atmospheric oxidation divalent manganesetion slowly adds ammoniacal liquor, and ammoniacal liquor adds the speed basis $\mathrm{pH}=\frac{1}{2}\lg k_{\mathrm{SP}}-\lg k_W-\frac{1}{2}\lg a_{{\mathrm{Mn}}^{2+}}$ (k in the formula _SPBe the solubility product constant of manganous hydroxide, kw is the ion-product constant of water) the formula decision.With the manganese ion concentration in the EDTA complexometric titration oxidation reaction process solution, calculate the pH of needs control at that time then according to following formula.Along with the carrying out of oxidizing reaction, manganese ion concentration is ever-reduced, in order to have guaranteed oxidizing reaction speed faster, avoids the mn ion hydrolytic precipitation again as far as possible simultaneously, requires pH according to the corresponding lentamente increase of calculated value, and reaction end pH is 6.After oxidizing reaction finishes, filter, oven dry gets the trimanganese tetroxide product.

Embodiment 2

With the 800ml manganese ion concentration is the reactor that the manganese chloride solution of 30g/L places 1500ml, is heated to 40 ℃, stirs, and drum atmospheric oxidation divalent manganesetion slowly adds ammoniacal liquor, and ammoniacal liquor adds the speed basis $\mathrm{pH}=\frac{1}{2}\lg k_{\mathrm{SP}}-\lg k_W-\frac{1}{2}\lg a_{{\mathrm{Mn}}^{2+}}$ (k in the formula _SPBe the solubility product constant of manganous hydroxide, kw is the ion-product constant of water) the formula decision.With the manganese ion concentration in the EDTA complexometric titration oxidation reaction process solution, calculate the pH of needs control at that time then according to following formula.Along with the carrying out of oxidizing reaction, manganese ion concentration is that formula is ever-reduced, in order to have guaranteed oxidizing reaction speed faster, avoids the mn ion hydrolytic precipitation again as far as possible simultaneously, requires pH according to the corresponding lentamente increase of calculated value, and reaction end pH is 12.After oxidizing reaction finishes, filter, oven dry gets the trimanganese tetroxide product.

Embodiment 3

With the 800ml manganese ion concentration is the reactor that the manganese sulfate solution of 50g/L places 1500ml, is heated to 60 ℃, stirs, and drum atmospheric oxidation divalent manganesetion slowly adds ammoniacal liquor, and ammoniacal liquor adds the speed basis $\mathrm{pH}=\frac{1}{2}\lg k_{\mathrm{SP}}-\lg k_W-\frac{1}{2}\lg a_{{\mathrm{Mn}}^{2+}}$ (k in the formula _SPBe the solubility product constant of manganous hydroxide, kw is the ion-product constant of water) the formula decision.With the manganese ion concentration in the EDTA complexometric titration oxidation reaction process solution, calculate the pH of needs control at that time then according to following formula.Along with the carrying out of oxidizing reaction, manganese ion concentration is ever-reduced, in order to have guaranteed oxidizing reaction speed faster, avoids the mn ion hydrolytic precipitation again as far as possible simultaneously, requires pH according to the corresponding lentamente increase of calculated value, and reaction end pH is 7.After oxidizing reaction finishes, filter, oven dry gets the trimanganese tetroxide product.

Embodiment 4

With the 800ml manganese ion concentration is the reactor that the manganese sulfate solution of 60g/L places 1500ml, is heated to 80 ℃, stirs, and drum atmospheric oxidation divalent manganesetion slowly adds ammoniacal liquor, and ammoniacal liquor adds the speed basis $\mathrm{pH}=\frac{1}{2}\lg k_{\mathrm{SP}}-\lg k_W-\frac{1}{2}\lg a_{{\mathrm{Mn}}^{2+}}$ (k in the formula _SPBe the solubility product constant of manganous hydroxide, kw is the ion-product constant of water) the formula decision.With the manganese ion concentration in the EDTA complexometric titration oxidation reaction process solution, calculate the pH of needs control at that time then according to following formula.Along with the carrying out of oxidizing reaction, manganese ion concentration is ever-reduced, in order to have guaranteed oxidizing reaction speed faster, avoids the mn ion hydrolytic precipitation again as far as possible simultaneously, requires pH according to the corresponding lentamente increase of calculated value, and reaction end pH is 8.After oxidizing reaction finishes, filter, oven dry gets the trimanganese tetroxide product.

Embodiment 5

With the 800ml manganese ion concentration is the reactor that the manganese sulfate solution of 70g/L places 1500ml, is heated to 50 ℃, stirs, and drum atmospheric oxidation divalent manganesetion slowly adds ammoniacal liquor, and ammoniacal liquor adds the speed basis $\mathrm{pH}=\frac{1}{2}\lg k_{\mathrm{SP}}-\lg k_W-\frac{1}{2}\lg a_{{\mathrm{Mn}}^{2+}}$ (k in the formula _SPBe the solubility product constant of manganous hydroxide, kw is the ion-product constant of water) the formula decision.With the manganese ion concentration in the EDTA complexometric titration oxidation reaction process solution, calculate the pH of needs control at that time then according to following formula.Along with the carrying out of oxidizing reaction, manganese ion concentration is ever-reduced, in order to have guaranteed oxidizing reaction speed faster, avoids the mn ion hydrolytic precipitation again as far as possible simultaneously, requires pH according to the corresponding lentamente increase of calculated value, and reaction end pH is 5.After oxidizing reaction finishes, filter, oven dry gets the trimanganese tetroxide product.

Claims (3)

1. the free divalent manganesetion of a direct oxidation prepares the method for trimanganese tetroxide, it is characterized in that selecting for use the scavenging solution of manganese ore pickling liquor, be that manganese sulfate solution or manganese chloride solution are raw material, make neutralizing agent with ammoniacal liquor, control the lift velocity of pH value of solution value in the whole oxidation reaction process, the lift velocity control of reaction process pH is according to pH and mn ion activity alpha _Mn ²⁺Relational expression $\mathrm{pH}=\frac{1}{2}\lg k_{\mathrm{SP}}-\lg k_W-\frac{1}{2}\lg a_{{\mathrm{Mn}}^{2+}}$ Decision, k in the formula _SPBe the solubility product constant of manganous hydroxide, k _wBe the ion-product constant of water, the manganese ion concentration with in the EDTA complexometric titration oxidation reaction process solution can calculate the unhydrolyzed pH value of mn ion in the solution by this formula, requires the pH value of solution value less than calculated value, to avoid the hydrolysis of mn ion; The pH of solution is controlled at 3～12 in the entire reaction course.

2. prepare the method for trimanganese tetroxide according to the free divalent manganesetion of claim 1 direct oxidation, it is characterized in that the oxidizing reaction temperature scope is 30～95 ℃.

3. prepare the method for trimanganese tetroxide according to the free divalent manganesetion of claim 1 direct oxidation, it is characterized in that the used oxygenant of oxidation divalent manganesetion is air and oxygen.