Non-Cyanide Base Electro Chemical Polishing

Abstract

A system used in polishing the metal includes a base assembly and an electrolytic cell assembly. The base assembly has a support stand which is mounted on to a connecting element. The base assembly further includes a holding cylinder that is provided with a hook or similar kind of means that is adapted to hold an anode fixture. A process of polishing the metal using system includes providing stripping solution which is free of cyanide is taken in a glass beaker of the electrolytic cell assembly and is heated. Further, the products that are to be polished are mounted on to the anode fixture using the plurality of hooks.

Description

FIELD OF INVENTION

The embodiments of this invention relate to jewelry manufacturing and, more particularly but not exclusively the embodiments of this invention relate to a method of polishing the jewelry during the course of manufacturing the jewelry.

BACKGROUND OF INVENTION

Jewelry industry at present is on the rise all over the world. Increase in demand for jewelry requires the jewelry manufacturing industries to optimize the methods of manufacturing jewelry to produce more jewels in minimum duration of time thereby meeting the expectations of the customers. Further, huge demands are imposed on the quality of the jewelry especially the high reflectivity of the surface of the jewelry product.

Generally, the jewelry product is polished before it is sent to the market so that the surface of the jewelry product will have a fine finish and a high reflectivity. Conventionally, the process of polishing the metal is performed by manual buffing using different kind of cotton, abrasive wheels with chemical compounds and so on in order to get the mirror finish for jewelry products.

Another existing method for polishing the jewelry is the process of electrochemical polishing using cyanide solution. The electrochemical polishing using cyanide solution is performed by using a cell that comprises of two electrodes namely positive electrode (anode) and negative electrode (cathode) that are electrically connected and immersed in a cyanide base solution (electrolyte). Further, the metal to be polished is connected to the positive electrode such that when an electrical current is passed through the cell, the excess metal from the positive electrode (anode) is removed and get dissolved in the electrolyte.

The cyanide electrolyte used in the conventional method for polishing the metal as discussed above is toxic thereby making the whole process hazardous, which demands the entire polishing process to be handled with caution. Also, residual cyanide sludge has become an increasing concern for metal finishers as the disposal options for cyanide-bearing sludge are limited, time consuming and are of high costs. Further, in case of mass production, the overall time consumption will be high affecting the overall efficiency of the process. Further, the conventional method of polishing results in fumes due to the passage of ions in the electrolytic cell. The fumes created in the electrolytic cell contain suspended particles that are hazardous to health and may cause environmental problems.

Further, the conventional methods for polishing the metal are not efficient in polishing the complex shaped jewels such as jewels with grooves and this in turn makes the whole process partially inefficient. Furthermore, in the conventional method for polishing the gold jewelry, the gold lost during the process of polishing cannot be recovered completely, which results in the gold loss.

Therefore, there is a need for a system in jewelry manufacturing industries that can overcome the above mentioned drawbacks thereby assuring better efficiency. Further, there is a need for a system that can be used for polishing the metal more efficiently.

OBJECT OF INVENTION

The principal object of the invention is to provide an environmental friendly system for polishing the metal.

Another object of the invention is to provide a system for polishing the metal that can be used for mass production.

A further object of the invention is to provide a system that is capable of removing hazardous fumes that are generated during the course of polishing the metal.

Yet another object of the invention is to provide a system for polishing the metal where the metal loss is minimized to a negligible amount.

BRIEF DESCRIPTION OF FIGURES

This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

FIG. 1 depicts a perspective view of a system for polishing metal according to an embodiment of the present invention;

FIG. 2 depicts a flowchart that describes the process of polishing the metal according to the embodiments of the present invention;

FIG. 3 depicts a system that is capable of removing hazardous fumes that are generated during the course of polishing the metal according to an embodiment of the present invention.

DETAILED DESCRIPTION OF INVENTION

The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The embodiments herein provide an environmental friendly system for polishing metal. Further, the embodiments herein provide an electric tractor that could enable multi speed transmissions. Furthermore, the embodiments herein provide a system that is capable of removing hazardous fumes that are generated during the course of polishing the metal. Referring now to the drawings, and more particularly to FIGS. 1 through 3, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

FIG. 1 depicts a perspective view of a system for polishing metal according to the embodiments of the present invention. The system 100 includes a base assembly 102 and an electrolytic cell assembly 130. The base assembly 102 includes a support stand 104 which may be made of wood or other insulating material. The support stand 104 is mounted on to a connecting element 106. The connecting element 106 further extends from the support stand 104 to a wheel 108 that is used to move, rotate and fix the system 100 to the ground. Further, the base assembly 102 includes a pillar 112 having a first end 112a and a second end 112b. The second end 112b of the pillar 112 is connected to the support stand 104 through an extension 110. Further, the first end 112a of the pillar 112 is connected to a first end 116a of a shaft 116 through a swelling joint 114. The shaft 116 extend in the axis perpendicular to the axis of the pillar 112 and the swelling joint enables the shaft 116 to revolve by 360 degree along the axis indicated by an arrow 115. Further, the second end 116b of the shaft 116 is connected to a plurality of cylinders 120 through a rotor 118. The rotor 118 is adapted to provide rotary motion to the plurality of cylinders 120 along the axis and direction indicated by an arrow 119. The base assembly 102 further includes a holding cylinder 122 that is provided with a hook 124 or similar kind of means that is adapted to hold an anode fixture 134.

Further, the electrolytic cell assembly 130 includes a glass beaker 132 that is adapted to enclose the anode fixture 134, a cathode strip 136, a heater with thermostat 142 and a non cyanide base stripping solution (not shown). The anode fixture 134 is provided with the hook 126 or similar kind of means at its top end 134a that is adapted to hold the anode fixture 134 to the holding cylinder 122. Further, the portion of the anode fixture 134 that is positioned inside the glass beaker is provided with the plurality of hooks 138 that is arranged in a sequence of row and adapted to hold the products that is to be polished (not shown). However, it should be noted that the anode fixture 134 may have different design and structure without otherwise deterring the intended function of the system 100 as will be apparent from the description of the embodiments of the invention. Such anode fixture 134 having different design and structure is also within the scope of this invention. Further, the electrolytic cell assembly 130 includes plurality of cathode strip 136 that is provided in between the anode fixture 134 and the glass beaker 132. The heater with thermostat 142 is electrically connected to the control panel rectifier unit 126, for example, the heater with thermostat is connected to the control panel rectifier unit by means of the cable 128. The control panel rectifier unit is used to control the parameters such as voltage, temperature etc and is used to convert the alternating current into the direct current.

FIG. 2 depicts a flowchart that describes the process 200 of polishing the metal according to the embodiments of the present invention. The stripping solution that is free of cyanide (for ex. thiourea based solution) is taken in the glass beaker 132 of the electrolytic cell assembly 130 and it is heated till 80 degree Celsius (step 201). In an embodiment, the stripping solution is prepared by homogeneous mixture of desired quantity of distilled water, thiourea, reducing sugar, activating acid and wetting agent in a suitable container. In an embodiment, one liter of distilled mineral water is taken in a glass beaker or similar kind of means. The distilled water is preheated to about 75 degree Celsius. Further, 65 grams of thiourea is added to the preheated water and stirred for complete dissolution. Further, 100 grams of reducing sugar is added to the mixture of thiourea and distilled water. The addition of reducing sugar reduces the temperature of stirring solution. Furthermore, 40 ml of activating acid and about 30 ml to 50 ml of wetting agent is added to the solution of thiourea, distilled water and reducing sugar and stirred properly for homogenous mixture. It should be noted that the aforementioned steps for preparing the stripping solution are provided for the ease of understanding of the embodiments of the invention. However, various steps provided in the above method may be performed in the order presented, in a different order, or simultaneously. Further, in some embodiments, one or more steps listed in the above method may be omitted. Therefore, such embodiments and any modification that is apparent from this description and drawings are also within the scope of this invention. FIG. 3 is a flowchart depicting the method of preparing stripping solution according to an embodiment of the present invention.

Further, the products that are to be polished are mounted on to the anode fixture 134 (step 202) using the plurality of hooks 138. For instance, the anode fixture is designed to hold nine products at a time that are to be polished. In an embodiment, anode fixture is a titanium jig. However, it should be noted that the anode fixture 134 may have different design and structure without otherwise deterring the intended function of the system 100 as will be apparent from the description of the embodiments of the invention. The anode fixture 134 along with the products that are to be polished is mounted on to the holding cylinder 122 through the hooks 124, 140. Further, the cathode strip 136 that is preferably made of stainless steel plate is placed inside the glass beaker 132 such that it is positioned in between the anode fixture 134 and the glass beaker 132. However, the cathode strip 136 can be selected from any one of the metals such as titanium plates, gold plates and platinum plates. The area of the anode and the area of the cathode are maintained preferably in 1:1 ratio. Further, the cathode strips 136 and anode fixture 134 is placed in the glass beaker 132 of the electrolytic cell assembly 130 in such a manner that the cathode strips 136 encircle the anode fixture 134 or vice versa. However, it should be noted that the anode fixture 134 and the cathode strips 136 may be positioned in different ways in the glass beaker 132 of the electrolytic cell assembly without otherwise deterring the intended function of the system 100 as will be apparent from the description of the embodiments of the invention. Further, the cathode strips 136 are connected to the negative terminal and the anode fixture 134 is connected to the positive terminal (step 203).

Further, the voltage of about 15-18 volts is applied to the electrolytic cell assembly 130 for about 2 mins (step 204). The voltage is applied, controlled and monitored through the control panel rectifier unit 126. Further, upon applying desired voltage, the anode fixture is rotated closer to the cathode stip. The voltage applied, results in etching/removing of the excess metal from the anode fixture and the removed/etched metal is deposited in the stripping solution (step 205). In another embodiment, the metal removed from anode is deposited in the cathode. The process of depositing metal on to the cathode is similar to that of plating. So that, this process can also be used in plating operations (where the metal is deposited on to the product in order to give a fine finish to the product) in addition to the polishing operations (where the metal is excess metal is removed from the product in order to give a fine finish to the product).

The electrochemical polish is carried out and the anode fixture is removed from the holding cylinder 122. The pillar 114 and the support stand 116 can be rotated along the respective axis as explained above so that the anode fixture 136 can be mounted on and removed off the holding cylinder with ease. After the electrochemical polishing process is performed, the products are removed from the anode fixture and the polished products on the anode fixture are replaced with the next batch of unpolished products (step 206). This process (steps 203, 204, 205 & 206) iterates until all the products are polished. It should be noted that the aforementioned steps for polishing the metal are provided for the ease of understanding of the embodiments of the invention. However, various steps provided in the above method may be performed in the order presented, in a different order, or simultaneously. Further, in some embodiments, one or more steps listed in the above method may be omitted. Therefore, such embodiments and any modification that is apparent from this description and drawings are also within the scope of this invention.

Further, the excess gold that are removed from the product and deposited on the cathode during the process of polishing will peel up in to the bottom of the bath after multiple batches of products are polished using the non-cyanide base electrochemical polishing method as mentioned above. The bath is then decanted to collect the gold and the collected gold is then washed with water and melted in the furnace for the solid gold recovery which will be almost 100% (step 207). In another embodiment, the system 100 has the cathode strips 136 and the anode fixture 134 that are provided in 1:2 ratio.

In another embodiment, the system 100 includes a scrubber unit 144. FIG. 3 depicts a system that is capable of removing hazardous fumes 143 that are generated during the course of polishing the metal according to an embodiment of the present invention. The scrubber unit 144 includes a bulb 146 and scrubber water 148. In an embodiment, the scrubber water is a distilled mineral water. Further, the scrubber unit 144 is provided in the system 100 such that it allows the passage of fumes 143 that are produced in the electrolytic cell assembly 130 during the course of plating process. In an embodiment, the fumes 143 produced in electrolytic cell assembly 130 are passed into the scrubber unit 144 by means of a vent 150. The scrubber unit 144 further includes tubing 152 that enables vapor communication between the bulb 146 and scrubber water 148. In an embodiment, fumes 143 produced in the electrolytic cell assembly 130 include suspended particles that are hazardous to environment. The bulb 146 acts as a mist eliminator and configured to remove acidic material from the fumes 143. The scrubber water 148 is configured to receive the fumes 143 from bulb 146 via tubing 152. Further, the scrubber water 148 removes all the suspended particles from the fumes 143, thereby provides clean air 153. Further, the clean air 153 is vented into atmosphere.

The process of removing hazardous fumes that are generated during the course of polishing the metal according to an embodiment of the present invention includes the steps of powering the scrubber unit 144. In an embodiment, the scrubber unit 144 is powered by control panel rectifier unit 126. Further, the scrubber unit 144 is powered before starting the polishing process in electrolytic cell assembly 130. The PH value of scrubber water 148 is measured. Further, if the scrubber water 148 is identified as acidic, new distilled water is utilized as scrubber water 148. Further, the electrochemical polishing as disclosed by method 200 is performed and the fumes produced during the course of electrochemical polishing is passed into the bulb 146 via vent 150. Further, the bulb 146 acts as a mist eliminator and removes acidic material from the fumes. The scrubber water 148 is configured to receive the fumes from bulb 146 via tubing 152. Further, the scrubber water 148 removes all the suspended particles from the fumes, thereby provides clean air 153. Further, the clean air is vented into atmosphere 153.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

1. A system for polishing metal, said system comprising:

an electrolytic cell assembly having: an anode fixture that is connected to a positive terminal and configured to receive plurality of metal to be polished; a cathode that is connected to a negative terminal; and a stripping solution that is configured to enable movement of ions between said anode fixture and said cathode,

wherein said stripping solution is free of cyanide.

2. The system as claimed in claim 1, wherein said anode fixture is selected from titanium jig.

3. The system as claimed in claim 1, wherein said cathode is selected from stainless steel.

4. The system as claimed in claim 1, wherein area of said anode fixture and said cathode is maintained at 1:1 ratio.

5. The system as claimed in claim 1, wherein said stripping solution is thiourea based solution.

6. The system as claimed in claim 1, wherein said stripping solution is a homogenous mixture of thiourea and at least one of distilled water, reducing sugar, activating acid and wetting agent.

7. The system as claimed in claim 1, further comprising a scrubber unit that is provided in vapor communication with said electrolytic cell assembly, wherein said scrubber unit comprises:

a bulb that is configured to remove acidic material from fumes produced in said electrolytic assembly; and

a scrubber water that is configured to remove suspended particles from fumes produced in said electrolytic assembly.

8. A method for polishing metal, said method comprising:

preparing a stripping solution;

preheating said stripping solution;

providing an anode connected to a positive terminal and cathode connected to a negative terminal in said stripping solution; and

providing desired voltage to said anode and said cathode,

wherein said anode includes plurality of metals to be polished, and

wherein said stripping solution is free of cyanide.

9. The method for polishing metal as claimed in claim 8, further comprising a process of cleaning fumes that are produced during said polishing metal.

10. The method for polishing metal as claimed in claim 9, wherein said stripping solution is a homogenous mixture of thiourea and at least one of distilled water, reducing sugar, activating acid, and wetting agent.