CN101235521A - A kind of energy-saving anode for non-ferrous metal electrowinning - Google Patents

Abstract

An energy saving anode used in electro-deposition of nonferrous metal is characterized in that the energy saving anode used in electro-deposition of nonferrous metal comprises a metal-conductive base-plate and at least one block of composite structure which is compounded by a metal layer with porous structure, wherein the structure is frame type, sandwich type and slab lattice type. The energy saving anode not only can effectively reduce true current density of the anode in electro-deposition of the nonferrous metal, reduce overpotential for oxygen evolution of the anode and lower energy consumption, but also can reduce the quality of the anode, reduce the creep deformation and the deformation of the anode, form a more dense oxydic film on the surface, reduce the corrosion rate of the anode, extend the service length of the anode and improve the quality of the cathode products. The energy saving anode can make a full use of the existing anode without changing the structure of the groove and have no effect to the process flow, and the energy saving anode has low preparing cost and low investment.

Description

A kind of energy-saving anode for non-ferrous metal electrowinning

technical field

The invention belongs to the field of hydrometallurgy, in particular to an anode for non-ferrous metal electrowinning.

Background technique

In the hydrometallurgy process of copper, zinc, manganese, nickel, cobalt, chromium and other metals, electrodeposition is the main energy-consuming process of the whole process, and the anode is one of the key components of the electrodeposition process. The choice of its material not only directly affects Power consumption and electrode life also affect the quality of cathode products. In general, electrode materials must meet the following requirements: good electrical conductivity, strong corrosion resistance, good mechanical strength and processability, and good electrocatalytic effect on electrode reactions. At present, the anodes used in the electrolysis industry include platinum (platinized titanium, sintered platinum) electrodes, lead dioxide electrodes, titanium-based oxide coating electrodes, magnetic iron oxide electrodes, graphite electrodes, lead and lead-based alloy electrodes, etc. However, in these electrodes, metal platinum and its alloys are expensive, and consume significantly when used at high current densities; lead oxide electrodes are difficult to manufacture and have poor corrosion resistance; titanium-based oxide-coated electrodes have not fundamentally solved the problem of titanium The passivation of the substrate has a short service life; the mechanical properties of the magnetic iron oxide electrode are poor, and it is difficult to enlarge it; the graphite electrode consumes a lot and has a high overpotential, so it has not been widely used. Lead and alloy anodes with lead as the main component have the advantages of easy molding and relatively stable in sulfuric acid medium, and are currently widely used in the production of non-ferrous metal industries. However, lead and lead-based alloy anodes have shortcomings such as high oxygen evolution overpotential (close to 1V) and surface passivation film is not dense, resulting in high electrolytic cell voltage (such as 3.2-3.8V for zinc electrowinning), and the current efficiency of the electrowinning process Low (75-90%), high energy consumption (such as zinc electrowinning is 3200-3800 kWh/ton), anode life is short (6-12 months), anode lead corrosion products easily enter the cathode product, affecting the quality of the cathode product and other shortcomings.

Contents of the invention

Aiming at the problems of high oxygen evolution overpotential, high energy consumption and serious lead pollution in cathode products in the electrowinning process of nonferrous metals, the present invention provides an energy-saving anode for nonferrous metal electrowinning with a new structure. The anode of this type of structure has a low anode It has the characteristics of overpotential, corrosion resistance, long life, light weight, easy manufacture and sufficient strength.

The structure of the present invention is characterized in that it is a composite structure composed of a conductive metal substrate and at least one metal layer with a porous structure, and the metal layer with a porous structure is connected to any one side or both sides of the conductive metal substrate by surface contact in a single or multiple ways , and can also be embedded in a single or multiple conductive metal substrates. Such an anode structure may preferably be frame, sandwich or grid. Among them, the double-layer anode is a composite structure formed by the porous metal layer 2 embedded in the conductive metal substrate 1; the sandwich-type anode is a composite structure formed by the conductive metal substrate 1 as the middle layer, and the porous metal layer 2 is distributed on both sides; the grid The type anode is a composite structure formed by conducting a metal substrate 1 as a grid, and a porous metal layer 2 is embedded in the grid.

The conductive metal substrate can be metal lead or lead-based alloy Pb-Me, wherein the alloy element Me is at least one of Ag, Ca, Sn, Sr, Sb, Ti, Al, Zn, Ce, Ba, and the alloy element content can be 0-50wt.%, the thickness is 0.5mm-8mm. The porous metal layer can be metallic lead or lead-based alloy Pb-Me', wherein Me' can be Ag, Ca, Sn, Sr, Sb, Ti, Al, Zn, Ce, Ba, Tl, Si, Mn, Co, The content of at least one of Fe may be 0.01wt.%-49.9wt.%, the thickness is 0.01mm-10mm, the porosity is 5%-85%, and the pore diameter is 0.01-5mm.

The invention can reduce the real current density of the anode, reduce the electrochemical polarization, reduce the oxygen evolution overpotential, save energy consumption and improve the current efficiency. When used in electrowinning of copper, zinc, manganese, nickel, cobalt, chromium, etc., the anode oxygen evolution overpotential can be reduced by 50-180mV, and the current efficiency can be increased by 1-10%. It can reduce the creep and deformation of the anode, make the oxide film formed on the surface denser, reduce the corrosion rate of the anode, and improve the quality of the electrowinning product. The meniscus liquid film formed at the three-phase interface is thinner, which increases the limit diffusion current density, reduces the concentration polarization, and improves the diffusion and mass transfer of the electrolyte. The method can make full use of the existing anode without changing the tank structure, does not affect the process flow, and has low preparation cost and low investment.

Description of drawings

Figure 1: Schematic diagram of frame-type anode structure;

Figure 2: Schematic diagram of the sandwich anode structure;

Figure 3: Schematic diagram of grid-type anode structure.

Labels in the figure: 1. Conductive metal substrate; 2. Porous metal layer

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1:

As shown in Figure 1, when a frame structure is used as a copper electrowinning anode, the conductive metal substrate is pure Pb with a thickness of 1mm; the porous metal layer is a Pb-Ca-Sn alloy with a thickness of 0.5mm and a porosity of 10%. , the pore diameter is 0.1-0.2mm, the Ca content is 0.12wt.%, and the Sn content is 1wt.%. The conductive metal substrate is metallurgically bonded to the porous metal layer to eliminate contact resistance. The anode of this structure is combined with the stainless steel cathode. When the electrolyte composition is 120g/L H ₂ SO ₄ , 45g/L Cu ²⁺ , the temperature is 25±0.5°C, and the current density is 250A/m ² . The voltage is 600mv, which is about 60mV lower than the oxygen evolution overpotential of Pb-based alloy anodes currently used in industry.

Example 2:

As shown in Figure 2, when a sandwich structure is used as a zinc electrodeposition anode, the conductive metal substrate is a Pb-Ag alloy with a thickness of 3mm and an Ag content of 0.3wt.%; the porous metal layers on both sides are Pb-Ag-Ca - Sr quaternary alloy with a thickness of 2mm, a porosity of 50%, a pore diameter of 0.7-0.9mm, and contents of Ag, Ca, and Sr of 0.3wt.%, 0.03wt.%, and 0.03wt.%, respectively. The conductive metal substrate is metallurgically combined with the porous metal layers on both sides to eliminate contact resistance. The anode of this structure is combined with the aluminum cathode. When the electrolyte composition is 160g/L H ₂ SO ₄ , 60g/L Zn ²⁺ , the temperature is 35±0.5°C, and the current density is 500A/m ² , the anode oxygen evolution is over The potential is 860mv, which is about 90mV lower than the oxygen evolution overpotential of Pb-based alloy anodes currently used in industry.

Example 3:

As shown in Figure 3, when the grid structure is used as the manganese electrodeposition anode, the metal conductive plate is a Pb-Sn alloy, the thickness is 6mm, and the Sn content is 40wt.%; the porous metal layer is Pb-Sb-Sn-Ag The quaternary alloy has a thickness of 8mm, a porosity of 80%, a pore diameter of 4.1-4.2mm, and Sb, Sn, and Ag contents of 1wt.%, 38wt.%, and 0.8wt.%. The conductive metal substrate is metallurgically bonded to the porous metal layer to eliminate contact resistance. The anode of this structure is combined with the titanium cathode. Under the conditions of electrolyte composition of 120g/L(NH ₄ ) ₂ SO ₄ , 17g/L Mn ²⁺ , pH value of 7, temperature of 40°C and current density of 800A/m ² During electrolysis, the oxygen evolution overpotential of the anode is 980mv, which is about 100mV lower than that of the Pb-based alloy anode currently used in industry.

Claims (7)

1. An energy-saving anode for electrowinning of non-ferrous metals, characterized in that: a composite structure consisting of a conductive metal substrate and at least one metal layer with a porous structure, the porous structure metal layer is connected by surface contact in a single or multiple manner On either side or both sides of a conductive metal substrate, or embedded in a conductive metal substrate. 2. The energy-saving anode for non-ferrous metal electrowinning according to claim 1, characterized in that: the composite structure composed of the porous metal layer is a frame type, that is, the composite structure formed by embedding the porous metal layer in the conductive metal substrate . 3. The energy-saving anode for non-ferrous metal electrowinning according to claim 1, characterized in that: the composite structure composed of the porous metal layer is a sandwich type, that is, the conductive metal substrate is the middle layer, and the porous metal layer is distributed on it Composite structure formed on both sides. 4. The energy-saving anode for non-ferrous metal electrowinning according to claim 1, characterized in that: the composite structure composed of the porous metal layer is a grid type, that is, the porous metal layer is embedded in a grid type conductive metal substrate to form composite structure. 5. The energy-saving anode for non-ferrous metal electrowinning according to claim 1, 2, 3 or 4, characterized in that: the conductive metal substrate is metallic lead or lead-based alloy Pb-Me, wherein the alloying element Me is Ag, Ca, At least one of Sn, Sr, Sb, Ti, Al, Zn, Ce, Ba; the porous metal layer is metal lead or lead-based alloy Pb-Me', wherein Me' is Ag, Ca, Sn, Sr, Sb, At least one of Ti, Al, Zn, Ce, Ba, Tl, Si, Mn, Co, Fe. 6. The energy-saving anode for electrowinning of non-ferrous metals according to claim 5, characterized in that: the alloy component Me content of the conductive metal substrate is 0-50wt.%, and the thickness is 0.5mm-8mm. 7. The energy-saving anode for non-ferrous metal electrowinning according to claim 5, characterized in that: the content of the alloy component Me' in the porous metal layer is 0.01wt.%-49.9wt.%, the thickness is 0.01mm-10mm, and the pores The ratio is 5% to 85%, and the pore diameter is 0.01mm to 5mm.

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