At present, there are more than 400 gold mines produced by the whole mud cyanide gold extraction process in China. If the cyanide tailings slurry is changed from the traditional method such as alkali chloride method into gold ore, the cyanide reduction and wastewater treatment technology and demonstration project development The processing technology can save hundreds of millions of dollars in processing costs per year.
Recently, one of the research and demonstration projects of the large-scale gold mining green mining and smelting technology of the â€œ12th Five-Yearâ€ National Science and Technology Support Project undertaken by the China Gold Group Corporation Changchun Gold Research Institute, â€œCalcium reduction and wastewater treatment in gold mining and smelting The technology and demonstrations were completed beyond the expected indicators and passed the acceptance of the expert group.
This project starts from the demand of major environmental protection technologies of common significance in the gold industry, and aims to solve the key technologies of the harmless treatment of cyanide-containing tailings produced in the whole mud cyanide gold extraction process, reaching the whole mud. The cyanide reduction of cyanide smelting and the purpose of recycling wastewater will guide the sustainable development of the gold industry.
Wei Huanan, manager of the Science and Technology Management Department of China National Gold Group Corporation and dean of the Changchun Gold Research Institute, said that the project was set up for problems such as cyanide-containing tailings slurry and tailings reservoir leaching solution. "After the technical treatment of Changchun Gold Research Institute, the tail Minerals and other minerals can meet national emission standards. These technologies have very good practical significance for gold mines that use cyanide to raise gold," he said.
Reduce cyanide throughput from the source
During the scientific research period, Changchun Gold Research Institute completed the development and engineering demonstration of gold mine smelting reduction and wastewater treatment technology through small-scale experimental research, expanded experimental research and demonstration engineering industrial experimental research.
The purpose of the small-scale test is to study the characteristics of cyanide tailings slurry in the whole mud cyanide-carbon slurry adsorption gold extraction process, to carry out comprehensive treatment technology research, and to develop technically feasible, environmentally satisfactory, and economically acceptable comprehensive treatment technology.
The small test concentrated 40% of the slurry to a concentration of 50%. According to the processing scale of 5150 tons/day of the cooperative mining enterprise Shaanxi Taibai Gold Mining Co., Ltd. (hereinafter referred to as â€œTaibai Companyâ€), due to the increase of slurry concentration, the slurry cyanide is 0.9255 tons/day compared with the slurry before concentration. The reduction was reduced to 0.6170 tons/day, and the reduction rate reached 33.33%. Concentration of the tailings slurry before treatment can not only reduce the volume of the tailings slurry, but also reduce the amount of cyanide treatment from the source and reduce the processing cost. It can also recycle the reduced amount of cyanide.
The purpose of the expanded test is to verify the results of small tests, solve the unresolved technical problems of small tests, and provide relevant technical parameters for demonstration engineering industry test research. Around this purpose, Changchun Gold Research Institute carried out cyanide stabilization pretreatment and cyanide stabilization pretreatment + inferior method test.
Expanded continuous test results show that cyanide stabilized pretreatment can reduce the total cyanide concentration of 122 mg / liter in the slurry to less than 5 mg / liter. The slurry after cyanide stabilization pretreatment is modified by inferior method or The OOT (a chemical code) method is used to treat environmental pollutants that meet the primary standard requirements of the Integrated Wastewater Discharge Standard (GB8978-1996).
Demonstration industrial continuous test research, the purpose is to verify the results of small-scale experiments and expanded experimental research, and at the same time demonstrate the technology in the form of demonstration projects, and rely on the demonstration project to conduct industrial continuous test research, through the process parameter optimization research as the industrial application of research results. provide technical support.
Demonstration industry continuous test results show that whether it is ventilation, agitation speed, stability and increased treatment volume, it is also the initial pH value, oxidant concentration, dosage study and catalyst dosage study, or low, medium and high dose studies and Very good results have been achieved in the study of harmful gas escape.
Open up new ways of harmless treatment
It is understood that through the above-mentioned technical research, the research team has established a demonstration plant for cyanide-containing slurry in the 200-cubic-meter-scale demonstration industrial plant in Taibai, which has mastered the core technology of China in this field and solved the key technologies. difficulty. Promote the development of clean production technology for the harmless treatment of cyanide tailings in the gold industry, and provide technical support for energy saving and emission reduction.
Through research, the research team successfully developed the "slurry sedimentation + cyanide stabilization pretreatment + inferior method" and "slurry sedimentation + cyanide stabilization pretreatment + OOT method" process technology for the first time, for the whole mud cyanide tailings slurry The harmless treatment has opened up new avenues. The cyanide tailings slurry treated by the above process can meet the first-class standard requirements in the Integrated Wastewater Discharge Standard (GB8978-1996), and the tailings can reach the general work.
Through this research, Changchun Gold Research Institute successfully applied for 129 patents, including 44 invention patents and 85 utility model patents. 98 patents have been granted in the application for patents, including 14 invention patents and 84 utility model patents.
The research team also formulated three standards during the research and development of this project. Among them, the "golden industry clean production evaluation index system" in the "golden industry (full mud cyanide process) clean production evaluation index system" standard 1, the standard draft for comments and preparation instructions have been issued by the National Development and Reform Commission; Including the gold industry standards, "Sodium Cyanide Safety Management Technical Specifications" (YS/T3017-2012) industry standard 1 item, "Ozone oxidation process reactor" (YS/T3016-2013) industry standard 1 item.
Through the research work of this subject, more than 20 young and middle-aged technical backbones have been cultivated. At present, it has become the main force of the Changchun Gold Research Institute, working in research positions such as project manager and technical responsibility.
Visible economic benefits
The ultimate goal of technology is to provide technical support for real production and life, as well as research on gold mines for smelting cyanide reduction and wastewater treatment technologies and demonstration projects.
During the â€œTwelfth Five-Year Planâ€ period, Changchun Gold Research Instituteâ€™s cyanide reduction technology and wastewater treatment technology were related to Yunnan Golden Group Heqing Beijiao Mining Co., Ltd. (currently the largest full mud cyanide gold extraction plant in China) Shandong Gold Mining (Laizhou) Co., Ltd. refinery (the largest gold concentrate cyanide plant in China) and Heilongjiang Baoshan Mining Co., Ltd. engineering application, tailings slurry harmless treatment related technology in Shandong Gold Returning Zhuang Mining Co., Ltd. and China The gold group Hebei Haoerya Gold Mining Co., Ltd. completed the semi-industrial expansion test and completed the engineering feasibility study report, with significant emission reduction effects and economic benefits.
At the same time, the "culp concentration + cyanide stabilization pretreatment + inferior method" and "slurry sedimentation + cyanide stabilization pretreatment + OOT (a chemical code) method" cyanide tailings slurry treatment technology, with good treatment effect, The processing cost is low, and the direct processing cost is only about 6 yuan / cubic meter.
At present, there are more than 400 gold mines produced by the whole mud cyanide gold extraction process in China. If the cyanide tailings slurry is changed from the traditional method such as alkali chloride method to the process technology developed by the project, it can save hundreds of millions of yuan every year. Processing costs. Zuo Yuming, a member of the research group, said in an interview with the reporter of China Gold News that he hopes that this advanced technology can be "overwhelmed everywhere" in the country: "At present, we are actively looking for suitable gold mining enterprises to negotiate and cooperate."
Environmental and social benefits
Most of the cyanide-containing tailings slurry of China's gold cyanide enterprises is transported along the gully pipeline to the tailings pond. Once a leak occurs, it will cause serious damage to the downstream surface water. After the cyanide-containing tailings slurry is treated by the research and development technology of this subject, it can meet the first-class standard requirements of the Integrated Wastewater Discharge Standard (GB8978-1996), and the tailings can meet the requirements of general industrial solid waste, which is no gold cyanide enterprise. Provide technical support for the construction of waste and less waste mines.
From the perspective of environmental safety, the cyanide-containing tailings slurry will greatly reduce the environmental risk of cyanide-containing slurry transport and cyanide-containing tailings in the storage of tailings ponds, even after cyanide treatment, using the process technology developed by the subject. When a leak occurs in the tailings slurry conveying process or an accident such as leakage or leakage occurs in the tailings pond, the environmental hazard will be minimized.
Therefore, research on gold ore cyanide reduction, wastewater treatment technology research and demonstration projects, environmental benefits are obvious in the harmless treatment of cyanide-containing tailings slurry, environmental risk prevention, comprehensive utilization of tailings resources and protection of local environment. .
At the same time, the series of technical research results obtained by Changchun Gold Research Institute is a breakthrough in China's environmental protection technology in gold mines. The â€œPulp Concentrate + Cyanide Stabilization Pretreatment + Infective Lawâ€ with independent intellectual property rights Compared with the existing technology at home and abroad, the process technology of â€œslurry sedimentation + cyanide stabilization pretreatment + OOT methodâ€ has more advantages and competitiveness in many technical aspects, and has expanded the comprehensive management of cyanide tailings slurry in China. The wider space provides a strong technical guarantee for the harmless treatment of cyanide tailings.
Long Zhenkun, deputy director of the Environmental Protection Institute of Changchun Gold Research Institute and member of the research group, said: "The technical treatment index is stable, and the cyanide-containing tailings slurry is directly treated. At the same time, the cyanide-containing wastewater and waste residue are treated harmlessly. Green treatment methods that do not cause secondary pollution, and the processing cost is also low."
When the gold ore smelting reduction and wastewater treatment technology are used in industrial applications, the project construction will drive the economic development of the region, and it can play an active role in improving the economic income of local residents and protecting the local environment. Solve the employment of some local people. Therefore, significant social benefits are also an achievement of this topic.
Wei Huanan pointed out: "This technology is first able to ensure compliance, and under the premise of ensuring compliance, the cost is the lowest compared with related technologies at home and abroad. At present, this technology is also leading internationally."
Broad application and prospects
In recent years, China's gold tailings accidents have occurred frequently. Since there is no effective harmless treatment process for the cyanide-containing tailings slurry, it is difficult to treat the cyanide-containing tailings slurry to meet the requirements of the Integrated Wastewater Discharge Standard (GB8978-1996), resulting in leakage or tailing during the transportation of cyanide-containing tailings slurry. When the mine leaks or leaks, the damage to the downstream environment is serious.
It is understood that it is difficult to improve the comprehensive utilization rate of gold cyanide tailings because it is difficult to treat the cyanide tailings harmlessly to meet the requirements of general industrial solid waste. Although after years of efforts, China has improved the treatment of cyanide-containing tailings slurry and comprehensive utilization of tailings, but the overall technical level of harmless treatment and comprehensive utilization of resources still lags behind the demand of gold industry development. Especially in the comprehensive utilization of cyanide tailings resources, due to the lack of acceptable technical expertise in processing costs, there are widespread problems such as limited consumption and low market efficiency of recycled products.
The National Medium- and Long-Term Plan for Science and Technology Development (2006-2020) specifies the development of environmental science and technology and puts forward the priority theme of â€œcomprehensive pollution control and waste recyclingâ€. Li Zhehao, director of the Environmental Protection Institute of Changchun Gold Research Institute and the head of the project, said that the process technology developed by this project will be used in the gold cyanide enterprise to achieve the standard treatment of cyanide-containing tailings and the harmless treatment and resources of cyanide tailings. Comprehensive utilization and other aspects have a very broad application prospects. â€œThe cyanide process mine will produce cyanide-containing waste residue and tailings. The high concentration of cyanide is very toxic. If it is not treated, it will have high environmental risks. Our technology will greatly reduce this risk and benefit the mine. Environment," he said.
With the implementation of the regulations of â€œWater Tenâ€, â€œTen Ten Articlesâ€ and â€œNew Dangerous Waste Listâ€, the state has become more and more strict on industrial and mining pollution control, and it is difficult to approve land acquisition procedures for tailings ponds of new construction, renovation and expansion projects. It is required that mining enterprises strengthen the treatment and disposal of industrial and mining wastes, and comprehensively rectify the disposal and storage of tailings. In particular, the â€œNew Dangerous Listâ€ defines cyanide tailings produced by gold mining companies using cyanide for gold beneficiation process as hazardous waste, which poses a severe test for gold mining enterprises adopting cyanidation process. Therefore, the organic combination of harmless treatment of cyanide tailings and mining and filling technology is an effective way for the sustainable development of the gold industry in the future.
The cyanide tailings harmless treatment technology system developed by Changchun Gold Research Institute just solves the problem of current safety and environmental protection and enterprise land acquisition difficulties for cyanide enterprises.
Opportunities are reserved for those who are prepared. The Changchun Gold Research Institute has taken the lead in the processing of tailings in gold mines through solid research in the early stage, and will definitely make important contributions to the sustainable development of the gold industry.
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