Process for recycling waste carbide

Abstract

The present invention provides a process for recycling waste carbide, wherein the waste carbide is directly used as anode and electrolyzed in the molten salt, comprising the following steps: 1) the vacuum dehydrating of the molten salt electrolyte; 2) electrolyzing the waste carbide, which is used as anode, and an inert electrode, which is used as cathode in the molten salt electrolyte with the electrolysis temperature of 3501000 C.; 3) separating and collecting the metal powder obtained by electrolysis from molten salt medium. According to the technical solutions of the present invention, tungsten and cobalt ions can be dissolved from the anode material-waste carbide directly into the molten salt medium and deposited on the cathode plate with being driven by the electrolysis voltage, to obtain the metal powder particles. The tungsten, cobalt and other products obtained by electrolysis can be used as carbide materials, high temperature structural materials, weapons materials, photocatalytic materials, etc., and can be applied to the fields of processing production, aerospace, military industry, environment and energy, and the like. This method has a short process, has no solid/liquid/gas waste emissions, and is environment-friendly.

Claims

1. An electrolytic process for recycling waste carbide, characterized in that, the waste carbide is directly used as an anode and electrolyzed in a molten salt electrolyte, comprising the following steps, without solid, liquid or gas waste emissions: 1) vacuum dehydrating the molten salt electrolyte; wherein the molten salt electrolyte is a compound of formula:
(x)A-(y)B(z)NaCl wherein, x is the mole percentage content of A; y is the mole percentage content of B; z is the mole percentage content of NaCl; x is in the range of 5 to 70 mol %; y is in the range of 0 to 60 mol %; z is in the range of 0 to 50 mol %; A is one or more selected from the group consisting of CaCl.sub.2), KCl and LiCl; and B is one or more selected from the group consisting of WCl.sub.6, WCl.sub.4, WCl.sub.2, Na.sub.2WO.sub.4, K.sub.2WO.sub.4 and CaWO.sub.4; 2) electrolyzing the waste carbide in the molten salt electrolyte via electrolysis having an electrolysis temperature of 350 to 1000 C., whereby a metal powder having a particle size in the range of 20 nm-500 m is produced, wherein the waste carbide is used as the anode in the electrolysis, and an inert electrode is used as a cathode in the electrolysis, wherein the anode and the cathode are submerged into the molten salt electrolyte, vertically parallel to one another, with a distance of at least 2 cm apart, and wherein the anode and the cathode do not overlap or intersect each other; wherein a protective gas is used during the electrolysis, wherein the protective gas is a mixed gas comprising one or more gases selected from the group consisting of oxygen, air, nitrogen and argon for W, WCo powder products, wherein the mixed gas comprises a volume content of oxygen in the range of 10-20%, and wherein the electrolysis comprises potentiostatic electrolysis in a cell having a cell voltage, and the cell voltage is controlled in the range of 2.8 to 3.2 V; and 3) separating and collecting the metal powder produced by the electrolysis from the molten salt electrolyte.

2. The process according to claim 1, wherein the cathode is selected from the group consisting of a titanium plate, a stainless steel plate, a carbon plate, and a graphite carbon.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1 is the schematic view of the electrolytic cell structure of the invention.

(2) FIG. 2 is the XRD pattern of the powder products obtained by electrolysis of YG6 waste carbide anode materials of in Example 1.

(3) FIG. 3 is the FESEM photo of the powder products obtained by electrolysis of YG6 waste carbide anode materials in Example 1.

(4) FIG. 4 is the XRD pattern of the powder products obtained by electrolysis of waste WC in Example 2.

(5) FIG. 5 is the FESEM photo of the powder products obtained by electrolysis of waste WC in Example 2.

(6) FIG. 6 is the XRD pattern of the powder products obtained by electrolysis of YG16 waste carbide anode materials in Example 3.

(7) FIG. 7 is the FESEM photo of the powder products obtained by electrolysis of YG16 waste carbide anode materials of in Example 3.

(8) In the figures: 1. sealed container, 2. air outlet, 3. electrolytic cell, 4. anode, 5. cathode, 6. air inlet.

EXAMPLES

(9) The present invention will be described by the following preferred embodiments. The skilled artisan should know that the examples are used only to illustrate the invention and are not intended to limit the scope of the invention.

(10) In the embodiments, unless otherwise specified, all the means used are conventional means in the art.

(11) In the present invention, the conventional apparatus in the art may be employed for electrolysis. The following examples employ the device shown in FIG. 1: electrolytic cell 3 is placed in a sealed container 1, the sealed container provides protective gas and electric heating. Container 1 is provided with a pressure detecting device P, a temperature detecting device T, an air inlet 6, an air outlet 2. An anode 4 and a cathode 5 are submerged into the electrolytic cell.

Example 1

(12) The method of preparing tungsten nano-powders by molten salt electrolysis to recycle waste carbide was used in the example. The electrolytic cell was protected with 10% oxygen+argon (by volume ratio). The molten salt system consisted of NaCl-52 mol % CaCl.sub.2 and the electrolysis temperature was 750 C. The titanium plate was used as cathode, and YG6 waste carbide was used as anode material with an electrode distance of 3 cm, the potentiostatic electrolysis was performed with a cell voltage of 3.2V, and the cell current during the electrolysis maintained constant at 1.3 A. As the anode material consumed, the cell current increased. The electrolysis was continued for 8 hours. The deposited metal powders after electrolysis were separated from the molten salt medium and collected by the methods of pickling, washing, filtrating and vacuum drying. The vacuum degree was 0.5 MPa, and the drying temperature was 50 C.

(13) The purity of the tungsten metal powders obtained by electrolysis reached 98.2 wt %, and the morphology of the metal tungsten powder was agglomerated spherical particles with size distribution in the range of 40400 nm. The XRD and FESEM results of the tungsten metal powders obtained by electrolysis were shown in FIG. 1 and FIG. 2, respectively. FIG. 1 shows the XRD pattern of the obtained powder products; FIG. 2 is the FESEM photo of the obtained powder products with 30,000 times magnification.

Example 2

(14) A method of directly recycling WC powders by molten salt electrolysis of waste WC carbide was used in the example. The electrolytic cell was protected with argon gas. The molten salt system consisted of NaCl-50 mol % KCl, and the electrolysis temperature was 750 C. The graphite carbon was used as cathode, and WC was used as anode material with an electrode distance of 3 cm. Galvanostatic electrolysis was carried out with a current density of 0.3 A/cm.sup.2. The cell voltage during the electrolysis remained at 2.2 V. The resulting metal powders after electrolysis was separated from the molten salt medium and collected by the methods of pickling, washing, filtrating and vacuum drying. The vacuum degree was 0.5 MPa, and the drying temperature was 50 C.

(15) The purity of the WC powder particles obtained by electrolysis reached 99.1 wt %. The XRD graph and FESEM photo of the product are shown in FIG. 4 and FIG. 5, respectively.

Example 3

(16) A method of directly preparing tungsten-cobalt alloy powders by molten salt electrolysis of waste carbide was used in the example. The electrolytic cell was protected with 20% oxygen+argon. The molten salt system consisted of NaCl-50 mol % Na.sub.2WO.sub.4-26 mol % CaCl.sub.2, and the electrolysis temperature was 750 C. The titanium plate was used as cathode, and YG16 waste carbide was used as anode material with an electrode spacing of 3 cm. Galvanostatic electrolysis was employed with a current density of 0.5 A/cm.sup.2, and the cell voltage during the electrolysis kept constant at 2.9 V. WCo composite powder particles were obtained by electrolysis. The resulting metal powders after electrolysis were separated from the molten salt medium and collected by the methods of pickling, washing, filtrating and vacuum drying. The vacuum degree was 0.5 MPa, and the drying temperature was 40 C.

(17) The XRD graph and FESEM photo of the product are shown in FIG. 6 and FIG. 7, respectively.

Example 4

(18) A method of directly preparing tungsten powders by molten salt electrolysis to treat waste carbide was used in the example. The electrolytic cell was protected with 20% oxygen+argon. The molten salt system consisted of LiCl-5 mol % NaCl-10 mol % Na.sub.2WO.sub.4-36 mol % CaCl.sub.2, and the electrolysis temperature was 500 C. The stainless steel plate was used as cathode, YG3 waste carbide of was used as anode material with an electrode spacing of 3 cm. Galvanostatic electrolysis was used with a current density of 0.05 A/cm.sup.2, and the cell voltage during the electrolysis kept constant at 1.2 V. The resulting metal powders after electrolysis were separated from the molten salt medium and collected by the methods of pickling, washing, filtrating and vacuum drying. The vacuum degree was 0.5 MPa, and the drying temperature was 40 C.

(19) Tungsten metal nano-particles were obtained by electrolysis, the purity of which reached 99.3 wt %.

Example 5

(20) A method of directly recycling WC nano-powders by molten salt electrolysis of waste YG10 carbide was used in the example. The electrolytic cell was protected with nitrogen. The molten salt system consisted of NaCl-4 mol % WCl.sub.2-40 mol % KCl, and the electrolysis temperature was 780 C. The carbon plate was used as cathode, and WC was used as anode material with an electrode distance of 3 cm. Galvanostatic electrolysis was used with a current density of 0.3 A/cm.sup.2, and the cell voltage during the electrolysis kept constant at 2.2 V. The resulting metal powders after electrolysis were separated from the molten salt medium and collected by the methods of pickling, washing, filtrating and vacuum drying. The vacuum degree was 0.5 MPa, and the drying temperature was 50 C.

(21) WC powder particles were obtained by electrolysis, the purity of which reached 98.1 wt %.

Example 6

(22) A method of directly preparing tungsten powders by molten salt electrolysis of waste carbide was used in the example. The electrolytic cell was protected with 10% oxygen+argon. The molten salt system consisted of LiCl-10 mol % NaCl-5 mol % Na.sub.2WO.sub.4-36 mol % CaCl.sub.2, and the electrolysis temperature was 500 C. The stainless steel plate was used as cathode, and waste YG3 carbide was used as anode material with an electrode distance of 3 cm. Galvanostatic electrolysis was used with a current density of 0.1 A/cm.sup.2, and the cell voltage during the electrolysis kept constant at 1.6 V. The resulting metal powders after electrolysis were separated from the molten salt medium and collected by the methods of pickling, washing, filtrating and vacuum drying. The vacuum degree was 0.5 MPa, and the drying temperature was 50 C.

(23) Tungsten metal nano-particles were obtained by electrolysis, the purity of which reached 99.3 wt %.

Example 7

(24) A method of directly preparing tungsten powders by molten salt electrolysis of waste carbide was used in the example. The electrolytic cell was protected with 10% oxygen+argon. The molten salt system consisted of LiCl-26 mol % KCl-5 mol % Na.sub.2WO.sub.4-10 mol % CaCl.sub.2, and the electrolysis temperature was 500 C. The stainless steel plate was used as cathode, and waste YG3 carbide of was used as anode material with an electrode distance of 3 cm. Galvanostatic electrolysis was used with a current density of 0.08 A/cm.sup.2, and the cell voltage during the electrolysis kept constant at 1.4 V. The resulting metal powders from electrolysis were separated from the molten salt medium and collected by the methods of pickling, washing, filtrating and vacuum drying. The vacuum degree was 0.5 MPa, and the drying temperature was 50 C.

(25) Tungsten metal nano-particles were obtained by electrolysis, the purity of which reached 98.7 wt %.

(26) The embodiments described above are merely preferred embodiments of the present invention, but not intended to limit the scope of the invention. Those skilled in the art may make various modifications and improvements to the technical solutions of the present invention without departing from the designing spirit, which all fall within the protection scope defined by the appended claims of the invention.

INDUSTRIAL APPLICABILITY

(27) The present invention discloses a process for recycling waste carbide, wherein the waste carbide is directly used as anode and electrolyzed in the molten salt, comprising the following steps: 1) the vacuum dehydrating of the molten salt electrolyte; 2) electrolyzing waste carbide, which is used as anode, and an inert electrode, which is used as cathode, in the molten salt electrolyte with the electrolysis temperature of 3501000 C.; 3) separating and collecting the metal powder obtained by electrolysis from molten salt medium. According to the technical solutions of the present invention, tungsten and cobalt ions can be directly dissolved from the anode material-waste carbide into the molten salt medium and deposited on the cathode plate with being driven by the electrolysis voltage, to obtain the metal powder particles. This method has a short process, has no solid/liquid/gas waste emissions, and is environment-friendly. The tungsten, cobalt and other products obtained by electrolysis can be used as carbide materials, high temperature structural materials, weapons materials, photocatalytic materials, etc., have a wide application field, and have an important effect in the fields of processing production, aerospace, military industry, environment and energy, and the like.