CN109306502B - Manganese electrolyte additive and using method thereof - Google Patents

Abstract

The invention discloses a manganese electrolyte additive and a using method thereof. Adding thiocyanate to SCN in conventional manganese electrolyte base solution (without selenium)^‑The mass percentage content of the copper-nickel alloy is 0.01-1.0 g/L, and the copper-nickel alloy is electrolyzed in a diaphragm electrolytic cell to obtain the copper-nickel alloy with flat surface, good crystallization and purity of 99.9 percentαThe electrolytic current efficiency of the-Mn crystal form metal manganese sheet reaches more than 70 percent. The thiocyanate additive provided by the invention has the advantages of low price, small dosage, high product purity, high current efficiency and the like, and is expected to replace the existing additive schemes of selenium dioxide, sulfur dioxide and the like, so the thiocyanate additive has great application and popularization values.

Description

Manganese electrolyte additive and using method thereof

Technical Field

The invention relates to a manganese metal electrolyte additive, in particular to a manganese electrolyte additive without selenium and sulfur dioxide and a using method thereof.

Background

When metal manganese is electrolyzed, in order to inhibit hydrogen gas from being separated out, improve current efficiency, promote the generation of stable crystal form alpha-Mn and obtain a bright and compact surface, additives such as selenium dioxide, sulfur dioxide and the like are generally required to be added into an electrolyte. Because the selenium resource is rare and expensive, the selenium has high toxicity to production workers and environment, and can enter electrolytic manganese through electrodeposition to influence the purity of the product; the sulfur dioxide additive easily causes the over-standard sulfur content in the product and the lower current efficiency. Therefore, many studies have been made on environmental-friendly additives free from selenium or sulfur dioxide, such as inorganic additives including boric acid, sodium hypophosphite, hydrogen boride, zinc ions, etc., and organic additives including hydroxylamine salts, carboxylic acid, gum arabic, polyacrylamide, ethylenediamine, phenol, etc. However, at present, no additive can completely replace selenium dioxide or sulfur dioxide to be used as an electrolytic manganese additive. China is a large country for producing electrolytic manganese, additive processes such as low selenium and sulfur dioxide are being implemented in the industry at present, but the problems of relatively complex additive composition, unstable process operation, low current efficiency and the like still exist. Therefore, research and development of the novel manganese electrolyte additive have important practical significance for the manganese metallurgical industry in China.

Disclosure of Invention

The invention aims to provide a selenium-free and non-sulfur dioxide type manganese electrolyte additive and a using method thereof.

The invention uses thiocyanate as the only additive of the manganese electrolyte, and does not use additive containing selenium, sulfur dioxide or other manganese electrolytes which are already researched and reported.

The using method of the manganese thiocyanate electrolyte additive comprises the following specific steps:

(1) preparing conventional manganese electrolytic base solution (specifically, containing (NH) by using commercially available analytical pure chemical reagent₄)₂SO₄ 100～130g/L、Mn²⁺Adding thiocyanate into 15-20 g/L aqueous solution of ions at the pH value of 7-8.4 and the temperature of 35-45 ℃ until SCN is obtained^-The mass content of the ions is 0.01-1.0 g/L, and the manganese thiocyanate electrolyte is obtained.

(2) The anode adopts a ruthenium oxide coating titanium sheet with the thickness of 10-20.0 cm multiplied by 6.0cm, and the cathode adopts a 316 type stainless steel sheet with the thickness of 10-20.0 cm multiplied by 3.0 cm; the electrolytic cell is a diaphragm electrolytic cell with two chambers, and the effective volumes of the cathode chamber and the anode chamber are both 300 mL.

(3) Pouring the manganese thiocyanate electrolyte obtained in the step (1) into the cathode chamber and the anode chamber of the electrolytic cell in the step (2) respectively in equal quantity, heating the electrolytic cell in water bath to 35 ℃, immersing the cathode plate and the anode plate into the electrolyte in equal depth, wherein the distance between the electrodes is 6.0cm, the effective electrolytic area ratio of the cathode to the anode is 1: 2, preserving heat in the water bath, switching on a direct current power supply, and adjusting the current density of the cathode to 200-500A/m²And electrolyzing for 2 hours, switching off a power supply, taking out the cathode sheet, immersing the cathode sheet into a potassium dichromate aqueous solution with the mass percentage content of 3%, passivating for 3 minutes, taking out and washing with tap water, and drying in an oven at the temperature of 80 ℃ for 30-60 minutes to obtain the electrolytic manganese metal sheet.

The current efficiency is calculated as follows:

η＝[(m_t-m₀)/(qAI_ct)]×100％

wherein η is the current efficiency; m is₀、m_tThe mass of the cathode before and after electrolysis is unit g; q is the electrochemical equivalent of the metal manganese of 1.025 g/(Ah); i is_cIs the current density, unit A/m²(ii) a A is the area of the cathode in m²(ii) a t is electrolysis time in h.

The thiocyanate is one or more of ammonium thiocyanate, potassium thiocyanate, sodium thiocyanate, magnesium thiocyanate, manganese thiocyanate and zinc thiocyanate.

The SCN^-The ions are selected from ammonium thiocyanate, potassium thiocyanate, sodium thiocyanate, magnesium thiocyanate, manganese thiocyanate, and zinc thiocyanateOne or more of them are dissolved in the electrolyte.

The thiocyanate is used as an additive, and the current efficiency of the electrolytic manganese can reach more than 70%. The metal manganese sheet obtained by electrodeposition is of an alpha-Mn crystal form, the Mn content by mass is up to 99.9%, the surface is smooth, the glossiness is good, and the crystal growth is regular. The thiocyanate additive provided by the invention has the characteristics of low price, small dosage, high product purity, high current efficiency and the like, is expected to replace the existing additive schemes of selenium dioxide, sulfur dioxide and the like, and has great application and popularization values.

Drawings

FIG. 1 is a photograph of the surface of an electrolytic manganese sheet according to example 1 of the present invention, wherein (a) is a digital photograph and (b) is a photograph of an optical microhardness tester (magnification: 40).

FIG. 2 is a scanning electron microscope (SE M) photograph of an electrolytic manganese sheet of example 2 of the present invention.

FIG. 3 is an X-ray diffraction pattern (XRD) of the electrolytic manganese sheet according to example 2 of the present invention.

Detailed Description

Example 1:

(1) 0.075g of potassium thiocyanate (KSCN) was dissolved in 500mL of a pre-formulated solution containing 50g of (NH)₄)₂SO₄And 30.8g MnSO₄·H₂In the water solution of O, 2.0moL/L dilute sulfuric acid and commercially available analytically pure ammonia water are used for adjusting the pH value to 8.0, and the potassium manganese thiocyanate electrolyte is obtained.

(2) The anode adopts a ruthenium oxide coating titanium sheet with the thickness of 10.0cm multiplied by 6.0cm, and the cathode adopts a 316 type stainless steel sheet with the thickness of 10.0cm multiplied by 3.0 cm; the electrolytic cell is a diaphragm electrolytic cell with two chambers, and the effective volumes of the cathode chamber and the anode chamber are both 300 mL.

(3) Respectively pouring the potassium manganese thiocyanate electrolyte obtained in the step (1) into the cathode chamber and the anode chamber of the electrolytic cell in the step (2) in equal amount, heating in water bath to 35 ℃, immersing the cathode plate and the anode plate into the electrolyte in equal depth, wherein the electrode spacing is 6.0cm, the effective electrolysis area ratio of the cathode to the anode is 1: 2, preserving heat in water bath, switching on a direct current power supply, and adjusting the current density of the cathode to 363.6A/m²Electrolyzing for 2 hours, cutting off the power supply, taking out the cathode plate, immersing the cathode plate into 3 percent potassium dichromate water solution for passivation for 3 minutes, taking out and using the cathode plateWashing with water, and drying in an oven at 80 ℃ for 60 minutes to obtain the electrolytic manganese metal sheet. The mass of the cathode plate before and after electrolysis is 3.5565 g and 4.4700g respectively, the purity of the manganese plate reaches more than 99.9 percent (mass ratio), and the current efficiency of the electrolytic manganese metal is calculated to be 74.3 percent. The manganese sheet has smooth and clean surface, regular crystal growth and uniform distribution of manganese crystal particles, and the surface digital camera picture (a) and the microhardness instrument picture (b) are shown in the attached figure 1.

Example 2:

(1) 0.3g of ammonium thiocyanate (NH)₄SCN) was dissolved in 500mL of a pre-prepared solution containing 50g (NH)₄)₂SO₄And 30.8g MnSO₄·H₂In the water solution of O, 2.0moL/L dilute sulfuric acid and commercially available analytically pure ammonia water are used for adjusting the pH value to 8.0, and the ammonium manganese thiocyanate electrolyte is obtained.

(2) The anode adopts a ruthenium oxide coating titanium sheet with the thickness of 20cm multiplied by 6.0cm, and the cathode adopts a 316 type stainless steel sheet with the thickness of 20cm multiplied by 3.0 cm; the electrolytic cell is a diaphragm electrolytic cell with two chambers, and the effective volumes of the cathode chamber and the anode chamber are both 300 mL.

(3) Respectively pouring the ammonium manganese thiocyanate electrolyte obtained in the step (1) into the cathode chamber and the anode chamber of the electrolytic cell in the step (2) in equal amount, heating in water bath to 35 ℃, immersing the cathode plate and the anode plate into the electrolyte in equal depth, wherein the distance between the electrodes is 6.0cm, the effective electrolysis area ratio of the cathode to the anode is 1: 2, preserving heat in water bath, switching on a direct current power supply, and adjusting the current density of the cathode to 400A/m²And electrolyzing for 2 hours, switching off a power supply, taking out the cathode sheet, immersing the cathode sheet into a potassium dichromate aqueous solution with the mass percentage content of 3%, passivating for 3 minutes, taking out and washing with tap water, and drying in an oven at 80 ℃ for 60 minutes to obtain the electrolytic manganese metal sheet. The mass of the cathode sheet before and after electrolysis is 3.5796 g and 4.4739g respectively, the purity of the manganese sheet reaches more than 99.9 percent (mass ratio), and the current efficiency of the electrolytic manganese metal is calculated to be 72.7 percent. The metal manganese sheet is a stable alpha-Mn crystal form, has no impurity phase, has a compact surface and good crystal growth, and has a surface Scanning Electron Microscope (SEM) picture as shown in figure 2 and an X-ray diffraction spectrum (XRD) as shown in figure 3.

Claims (1)

1. The use method of the manganese electrolyte additive is characterized by comprising the following specific steps:

(1) preparing conventional manganese electrolytic base solution containing (NH) by using commercially available analytical pure chemical reagent₄)₂SO₄ 100~130 g/L、Mn²⁺Adding thiocyanate into 15-20 g/L aqueous solution of ions at the pH value of 7-8.4 and the temperature of 35-45 ℃ to SCN^-The mass content of the ions is 0.01-1.0 g/L, and the manganese electrolyte containing the thiocyanate additive is obtained;

(2) the anode adopts a ruthenium oxide coating titanium sheet with the thickness of 10-20.0 cm multiplied by 6.0cm, and the cathode adopts a 316 type stainless steel sheet with the thickness of 10-20.0 cm multiplied by 3.0 cm; the electrolytic cell is a diaphragm electrolytic cell with two chambers, and the effective volumes of the cathode chamber and the anode chamber are both 300 mL;

(3) pouring the manganese thiocyanate electrolyte obtained in the step (1) into the cathode chamber and the anode chamber of the electrolytic cell in the step (2) respectively in equal quantity, heating in water bath to 35 ℃, immersing the cathode sheet and the anode sheet into the electrolyte in equal depth, wherein the electrode spacing is 6.0cm, and the effective electrolytic area ratio of the cathode to the anode is 1: 2, preserving heat in water bath, switching on a direct current power supply, and adjusting the cathode current density to 200-500A/m²Electrolyzing for 2 hours, switching off a power supply, taking out the cathode sheet, immersing the cathode sheet into a potassium dichromate aqueous solution with the mass percentage content of 3%, passivating for 3 minutes, taking out and washing with tap water, and drying in an oven at 80 ℃ for 30-60 minutes to obtain an electrolytic manganese metal sheet;

the thiocyanate is one or more of ammonium thiocyanate, potassium thiocyanate, sodium thiocyanate, magnesium thiocyanate, manganese thiocyanate and zinc thiocyanate.

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