one Foreword
The rapid development of gold industry, has made easy to smelt resource consumption Yi to do, all over the world are increasing their efforts to develop and hard to smelt gold extraction technique, known as refractory gold ores or gold extraction technology, the difficulty lies, hard smelt or gold concentrate, micro-fine gold to other materials in the wrapped state, as pyrite, arsenopyrite by normal grinding the gold can not be exposed, even if the ultra-fine grinding, usually Can't solve it. Therefore, a large part of the difficult metallurgical mines refers to arsenic-bearing gold or arsenic-bearing gold concentrates. In the past ten years, the development of pretreatment technology for refractory metallurgical mines has been continuously carried out worldwide.
The technologies that have reached the industrial application level include high-temperature calcination decomposition method, biological decomposition method, acid thermal decomposition method and alkali pressure thermal decomposition method; the technologies in the experimental stage include nitric acid decomposition method, vacuum pyrolysis method, and ammonia pressure thermal decomposition method. , microwave pyrolysis method and chlorine decomposition method.
If the roasting decomposition method does not consider the investment in the treatment of the three wastes, the equipment investment is small, the equipment manufacturing difficulty is also small, and the material requirements of the equipment are not high, so there is a certain market in the early stage. However, the production of a large amount of sulfur dioxide-containing waste gas and highly toxic solid arsenic trioxide (white peony) is more difficult to handle, so the environmental pollution is more serious, and the recovery rate of gold is lower than that of the other two pretreatment methods. 85% . Due to pollution problems, it is not suitable at present.
The biodegradation method is carried out under acidic conditions, requires constant temperature, and the equipment needs to be preserved. Since the reaction rate is very slow, it generally takes more than 120 hours, so the equipment investment is large and the production cost is high. For raw materials containing less arsenic and sulfur, the treatment effect is better, and the gold recovery rate is as high as 90% . However, for raw materials containing high arsenic and sulfur, the treatment time is long and industrially difficult to achieve.
Take the processing capacity of 50t / d equipment as an example, the equipment investment is more than 15 million yuan, and the production cost is not less than 600 yuan / t .
The acid thermal decomposition method refers to a sulfuric acid pressurization heating decomposition method. Its biggest advantage is that the treatment effect is good, and the general gold recovery rate can reach 95% . The reaction is in the range of 2% to 8% sulfuric acid,
In the unindustrial pretreatment method, the nitric acid decomposition process and equipment are still uncertain, and the production cost is high; the vacuum pyrolysis method has high power consumption, the production scale is not easy to expand, the gold recovery rate is not high enough; the ammonia pressure thermal decomposition method recovers ammonia, etc. The problem has not been solved, the recovery rate of gold is not high enough; the microwave pyrolysis method has large investment and difficult control, and it is still difficult to manufacture high-power microwave source; the chlorine decomposition method is difficult to prevent corrosion, when the sulfur or arsenic content is high, the chlorine consumption Too large, the production cost is too high.
In foreign countries, the production scale of gold mines is relatively large. Enterprises usually invest huge sums of money to establish facilities for handling difficult metallurgical mines. The treatment scale is above 1000t/d . Due to the large scale of treatment and relatively low processing cost, the sulfuric acid pyrolysis technology Biodegradation technology has been industrially applied abroad.
The characteristic of difficult metallurgical mines in China is that the reserves of individual mines are small. It is not suitable for large-scale pretreatment facilities from the economic point of view. At present, the price of gold is too low, and the profit of producing gold is limited. The intention of the technology to establish a pretreatment plant.
The development of industrial methods with Chinese characteristics for the treatment of refractory metallurgical ores, including gold concentrates, has broad market prospects. Its characteristics are that the equipment investment is small, the production cost is moderate (the production cost is high, but the total production cost can be accepted), the equipment manufacturing raw materials are based on domestic, easy to operate, and no environmental pollution.
two Sulfuric acid atmospheric decomposition technology
The invention adopts sulfuric acid with high boiling point as oxidant, supplemented by a small amount of other auxiliary agents, and performs temperature decomposition reaction of refractory metallurgical fine powder under normal pressure. Due to the reaction under normal pressure, the reaction equipment materials are easy to obtain and easy to manufacture.
The invention uses sulfuric acid as the reaction oxidant, reacts at the same temperature, decomposes the pyrite into ferrous sulfate, sulfur and thiosulfate; decomposes the arsenic pyrite into arsenate, arsenite, Sulfur, thiosulfate, may also produce a small amount of sulfur dioxide in the reaction. Since the generated sulfur volatilizes, it will not adversely affect the subsequent recovery of gold, and a small amount of gas generated can be treated by absorption, and arsenic in the resulting dregs exists in the form of insoluble ferro- vanadium , so that it does not pollute the environment.
LanZhou International Inland Port Of Multimodal Transportation.,Com , https://www.lzgjgdsly.com