Method for Synergistic Chlorination-Oxidation Leaching of Gold from Refractory Gold Ore:

This method for synergistic chlorination-oxidation leaching of gold from refractory gold ore belongs to the field of hydrometallurgy.

First, crush the gold ore into ore powder; fully mix the ore powder, sodium hydroxide, sodium hypochlorite and water to obtain ore slurry; introduce air into the slurry, and perform ultrasonic-enhanced leaching under stirring conditions.

During the enhanced leaching process, hydrogen peroxide is added periodically. The synergistic effect of hydrogen peroxide and sodium hydroxide is utilized to carry out redox reactions—their combined oxidation effect far exceeds that of either agent alone. 

This not only shortens the reaction time but also improves gold leaching efficiency, saving reagent costs while boosting overall ore leaching performance. The leaching rate can reach over 98% using this method. Using sodium hypochlorite as the leaching agent does not impose environmental pressure; additionally, this invention adopts a one-step enhanced leaching process, simplifying the leaching workflow.

The gold extraction process from copper-bearing oxidized gold ore falls under hydrometallurgical technology. First, the copper-bearing oxidized gold ore undergoes crushing, grinding and classification, followed by alkaline treatment. Then, a certain proportion of chelating agent and sodium cyanide are added to inhibit copper leaching and realize selective gold leaching. Finally, gold is extracted from the leachate via conventional activated carbon adsorption.

This method boasts a simple process, uncomplicated equipment and ease of implementation, along with high gold leaching rate, low reagent consumption, minimal capital investment and low cost. It is a gold extraction approach that is easy to industrialize and delivers good economic benefits.

Hydrometallurgy is another method for extracting copper from chalcopyrite. Due to its lower operating cost, it can be applied to the hydrometallurgical leaching of copper from low-grade copper ores. Common leaching agents are acidic chloride media and acidic sulfate media.

In sulfate media, the leaching kinetics are generally slow, and complete copper leaching is difficult to achieve. This is because a passivation layer forms on the mineral surface; additionally, a complex purification and impurity removal process is required.

In acidic chloride media, salts have high solubility in chloride-containing solutions, and copper ions can be stabilized in concentrated chloride systems. Thus, the leaching rate in chloride media is faster than in sulfate media. However, acidic chloride media have drawbacks: strong corrosivity, difficulty in electrowinning high-quality copper from them, and the need for complex purification and impurity removal processes after leaching.

Hydrometallurgical Process for Leaching and Electrowinning Copper from Oxide Copper Ores:

Process Description:

The process involves heap leaching copper oxides using sulfuric acid (H2SO4). After leaching, the resulting pregnant solution is neutralized with a base (e.g., NaOH) to precipitate copper as copper hydroxide (Cu(OH)2), which is then filtered and dissolved in sulfuric acid again to form a copper sulfate solution.

The copper sulfate solution undergoes leaching-electrowinning operations, including solvent extraction and electrorefining, to produce cathode copper.

Advantages of the Process:

In-situ Leaching: This method allows for the treatment of disseminated oxide copper ores that are difficult to process otherwise.

Concentrated Leaching-Electrowinning: By centralizing leaching and electrowinning operations, the process reduces transportation costs as it transitions from ore transport to tailings transportation.

Cost-Effectiveness: The process minimizes capital investment while achieving high efficiency in copper recovery.

Economic and Environmental Benefits: Reduces the need for ore transportation, lowering environmental impact and operational costs.

The leaching method of chalcopyrite belongs to the field of wet metallurgy technology, which includes the following steps:

1) Mixing chalcopyrite with alkali and smelting to obtain pre treated chalcopyrite;

2) Mix the pre treated chalcopyrite obtained in step 1) with acid solution, catalyst, and oxidant for oxidation leaching to obtain a copper containing leaching solution.

Firstly, alkali is used to melt chalcopyrite, causing changes in its lattice structure, making copper leaching easier, and reducing the leaching temperature for subsequent leaching; Adding catalysts and oxidants during the acid leaching process further reduces the leaching temperature, shortens the leaching time, and improves the leaching rate of copper. The results of the implementation example show that the leaching method provided by the present invention has a leaching temperature of 75 ℃ and a leaching time of 2 hours, and the leaching rate of copper reaches over 99.9%.

Hydrometallurgical Process for Concentrating Copper, Gold, and Silver from the Tailings of Sulfide Gold Ores After Cyanidation

Process Description:

The process utilizes calcium sulfide (CaS) and calcium arsenic oxide (Ca3AsO4), which are filtered or washed using a mist tower to remove dust before being discharged into the atmosphere.

After cyanidation, the tailings from sulfide gold ores are fed into a thickening slurry tank. Water is added to adjust the slurry concentration to 40-60%. Under ambient temperature and pressure, the mixture is continuously stirred to ensure uniformity.

Industrial sulfuric acid (H2SO4) is then added to adjust the pH of the slurry to 5. The slurry is stirred for 15-25 minutes to stabilize the pH before being transferred back to the thickening tank.

The slurry's concentration is adjusted to 20-30% with water and maintained at a pH of 6. This step involves continuous feeding and discharge of material.

While stirring, flotation reagents and an emulsifier (2# oil) are added uniformly to the slurry.

The slurry is then transferred to a flotation tank for closed-circuit operations, including primary roughing, secondary scavenging, and tertiary cleaning. Copper, gold, and silver are concentrated through this process.

The process is simple, efficient, cost-effective, with high metal recovery rates.

Requires low investment and demonstrates quick results.

Gas filled infiltration heap leaching method and process for secondary sulfide copper ore:

The secondary sulfide copper ore infiltration heap leaching method involves first laying an anti-seepage layer between the bottom pad and the retaining wall of the yard, then laying a collection pipe and a gravel layer, and finally laying an inflation pipeline and building the ore heap. The copper is extracted by leaching. The present invention embeds inflation pipelines in the process of building high clay ore piles, and efficiently introduces air into the interior of the yard through the inflation pipelines, thereby ensuring sufficient air inside the ore heap. 

At the same time, through the infiltration leaching method, high clay ore is immersed in the leaching solution for a long time, allowing the leaching solution, air, and high clay ore to fully contact each other for a long time, thereby ensuring efficient ore leaching. This allows high clay secondary sulfide copper ore to be produced using heap leaching, improving the utilization efficiency of copper resources.

The Method of Acid Heap Leaching for Oxidized Copper Ores

After the crushed and screened copper ore is sorted, the oversize material undergoes standard acid heap leaching. The undersize material is concentrated, thickened, and pelletized before being restacked for further leaching.

The solution rich in copper ions is extracted using solvent electrocoagulation to produce marketable cathode copper. After concentrating the undersize material, a binder is added to form slurry. The slurry is mixed with pre-prepared 5mm-25mm diameter acid-resistant crushed stone to form pellets for stacking on the heap.

During pelletizing and leaching operations, the pellet stack height is 3～5 meters, the dilute sulfuric acid concentration in the solution is between 0.1～2mol/L, the spraying intensity is 0.2-0.5 L/min, and each leaching cycle lasts for 1-2 months. This method effectively utilizes previously underutilized clay-containing copper ores with high mudstone-forming potential, thereby improving mining's overall utilization rate, reducing costs, and increasing profits.

Especially suitable for application in regions throughout China, particularly the copper ore-rich but challenging areas such as western high plateaus where oxidized copper ores are predominant.

A rapid leaching method for gold ore is employed, which involves breaking and grinding the gold ore to increase its surface area. The ore is then mixed with bromide salts, iron salts, and acid to form a leaching solution. Under ambient temperature and pressure conditions, this mixture is agitated for 10 to 20 minutes at a speed of 100 to 800 rpm. After agitation, the mixture is filtered to separate the residue from the leachate. The residue is washed, and the conventional method is used to recover gold from the filtered leachate.

This method allows for rapid gold extraction within a short time frame, typically achieving a leaching rate of over 90%. The process operates under normal temperature and pressure conditions, making it a straightforward production technique. It offers several advantages, including high efficiency, wide applicability to difficult-to-process ores such as high-sulfur, high-arsenic, and carbonaceous gold ores, and minimal environmental impact due to the absence of sulfur dioxide and oxidized arsenic emissions. Additionally, the reagents used are non-toxic.