Gold purification method

Abstract

Gold obtained as a result of the standard gold refining process may contain 0.1 - 0.2 ‰ silver and / or copper impurities. These impurities prevent obtaining gold with a purity of 99.9 ‰. In this process of the invention, a second chemical washing process is applied to the brown colored gold powders obtained as a result of the refining process, which is called cake form in the industrial terminology. Trace amounts of silver and copper are dissolved and removed from the gold by means of this chemical. The invention relates in particular to a gold purification method.

Description

[0001] GOLD PURIFICATION METHOD

[0002] TECHNICAL FIELD

[0003] Gold obtained as a result of the standard gold refining process may contain 0.1 - 0.2 %o silver and / or copper impurities. These impurities prevent obtaining gold with a purity of 99.9 %o. In this process of the invention, a second chemical washing process is applied to the brown colored gold powders obtained as a result of the refining process, which is called cake form in the industrial terminology. Trace amounts of silver and copper are dissolved and removed from the gold by means of this chemical. The invention relates in particular to a gold purification method.

[0004] BACKGROUND ART

[0005] Theoretically, ammonium hydroxide solution can chemically dissolve metals and metal salts such as silver, silver chloride and copper, but it does not react with gold. (C.M. Hoke-1940) (Guna-1994) (Redmehr-2013) (Diehl-1952)

[0006] In current applications, gold electrolysis is applied to the material obtained as a result of standard refining and containing trace amounts of impurities, as the process of making gold 999.9. However, the electrolysis process is both time consuming and costly due to the high amount of gold required in the electrolytic liquid required for electrolysis.

[0007] The refined gold obtained as a result of the refining process may be contaminated with impurities from the industrial tanks and leaching processes. These impurities are usually silver metal, copper metal and / or silver chloride salt. Current methods use gold electrolysis to remove these impurities from the refined gold.

[0008] The electrolysis method is a second refining method. In the electrolysis method, depending on the amount of gold to be processed, a certain amount of pure gold is used in the electrolyzer and this amount of gold always remains constant in the electrolyzer. For this reason, the operation cost is very high. Consequently, the need to overcome the disadvantages of the current state of the art and the disadvantages of the applications currently in use has entailed an improvement in the relevant technical field.

[0009] DESCRIPTION OF THE INVENTION

[0010] The present invention relates to a method of gold purification to eliminate the above-mentioned disadvantages and to bring new advantages to the relevant technical field.

[0011] In our method of the invention, electrolysis, which can be considered as a second refining process, is not applied. Instead, at the end of the standard refining process, a chemical wash is performed to remove trace amounts of copper and silver impurities and gold with a purity of %o999.9 (999.9 per thousand) is obtained. This washing process is not a separate refining process. This eliminates the waste of time. At the same time, since only dilute ammonium hydroxide solution is used during this chemical process, the operation cost is very low compared to the electrolysis refining method.

[0012] Brief Description of Drawings

[0013] The embodiments of the present invention, briefly summarized above and discussed in more detail below, may be understood with reference to the exemplary embodiments of the invention illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings only describe typical embodiments of the present invention and shall not be deemed to limit its scope, as the invention may, therefore, permit other equally effective embodiments.

[0014] For ease of understanding, identical reference numbers have been used where possible to indicate identical elements common to the figures. The figures are not drawn to scale and can be simplified for clarity. It is considered that elements and features of one embodiment can be usefully incorporated into other embodiments without the need for further explanation. Figure 1 : A graph of the change in gold purity versus different concentrations of NH4OH solution.

[0015] Figure 2: A graph of silver impurity change versus different concentrations of NH4OH solution.

[0016] §ekil 3: A graph of change in copper pollution versus different concentrations of NH4OH solution.

[0017] DETAILED DESCRIPTION OF THE INVENTION

[0018] In this detailed description, the preferred alternatives to the gold purification method embodiment of the invention are described only for the purpose of a better understanding of the subject matter and in a non-limiting manner.

[0019] In our method, there is no second refining process. The refined gold obtained from a single refining process and containing trace amounts of copper, silver and / or silver chloride impurities is washed with dilute ammonium hydroxide solution. The ammonium hydroxide solution chemically dissolves the copper, silver and silver chloride impurities and passes them into liquid form. When this liquid is filtered, the impurities are removed from the liquid.

[0020] In the study conducted in our laboratory, the gold sample obtained as a result of the standard refining process was washed with different concentrations of NH4OH solution. XRF analysis was performed on the refining sample before washing. The precious metal concentration determined as a result of this analysis contains trace amounts of silver and copper impurities. (Au=99.883%, Ag=0.053% Cu=0.051 %). Samples of 10 grams each of the refined product containing this impurity were washed with different concentrations of ammonium hydroxide (NH4OH) solutions. These different ammonium hydroxide concentrations used in the experiment are as follows: 3%, 5%, 7%, 10%, 10%, 12%, 15%. After washing with these NH4OH concentrations, the refined gold samples were filtered to remove the ammonium hydroxide solutions and then the samples were rinsed with hot water and filtered again. After rinsing, the refined gold samples were dried in a drying oven at 500 °C. The results of XRF analysis of the solids obtained after drying are shown in the table below.

[0021] Graphical distributions of these XRF results are also shown in the graphs in the figures.

[0022] AAS analysis was performed on NH4OH filtrates to determine the amount of copper and silver dissolved as a result of the washing processes. The results of AAS studies performed on ammonium hydroxide liquids are given in the table below.

[0023] As a result of the experimental studies, dilute NH4OH solution dissolves trace amounts of Silver, Silver Chloride and Copper metals, so that gold obtained by refining is easily purified from trace amounts of impurities and gold of 999.9 purity is obtained.

[0024] As can be seen in the experimental data, the highest yield is obtained at values between 2% and 7% concentration range.

[0025] Similar experimental studies to the one shared above were repeated at different times and in different quantities and similar results were obtained each time.

Claims

CLAIMS1- A method of purifying gold with a purity of 999.9 %o at the end of the standard refining process without electrolysis, which is considered a second refining process, characterized in that it includes the process steps of washing with diluted ammonium hydroxide (NH4OH) in the range of 2%-7% at the end of the standard refining process, filtering refined gold samples to remove ammonium hydroxide solutions, then filtering the samples again with hot water and after rinsing, drying the refined gold samples in a drying oven set at 500°C.

Images