Gold mineral resources is a major component of the reserves of gold resources, has important strategic significance. With the development of the gold industry and the increasing demand for gold at home and abroad, the reserves of easy-to-select metallurgical ore are depleted, and the difficulty in selecting metallurgical mines has become more and more important. According to the data, gold in the world's hard-to-select metallurgical mines accounts for 2/3 of the world's gold reserves [1] . The geochemical properties of arsenic and gold are destined to coexist in ore. Arsenic-bearing gold ore is widely distributed in China and has become an important resource for gold mine production. Minerals such as arsenic and antimony are extremely harmful to the cyanidation of gold, and tend to consume cyanide in large amounts or reduce the leaching efficiency of gold. In view of this, the in-depth arsenic removal research on arsenic-containing ore is of great significance both in environmental protection and in improving the efficiency of smelting and smelting. I. Research status and analysis of pretreatment of arsenic-containing refractory gold ore The so-called refractory gold ore generally refers to gold ore that has a cyanidation leaching rate of less than 80% without pretreatment. According to statistics, 5% of gold resources have an arsenic ratio of 2000:1 [1] . China has found arsenic-containing fine-grained gold-bearing gold deposits in many areas, mainly distributed in the two triangles of Yunnan, Guizhou, Guizhou and Shaanxi, Gansu and Sichuan. Its abundant reserves have made it a major gold in China. Mine type [2] . When the arsenic-containing gold ore is directly used in the cyanidation process, the cyanide consumption is large and the gold leaching rate is low. To extract the gold from such gold must advance arsenic removal, wrapped gold pyrite and arsenopyrite destruction, the gold leaching may become exposed state, thereby improving gold recovery [3]. In recent years, many units and scholars at home and abroad have carried out a lot of research work on the smelting process of arsenic-containing ores, and made significant progress [4] . It can be seen from the research route and application effect of difficult smelting technology in foreign countries that the so-called difficult smelting technology mainly refers to pretreatment technology. Pretreatment is a precondition for improving the gold leaching rate of arsenic-containing refractory gold ore. At present, the pretreatment methods that have been developed or applied to high-arsenic-sulfur gold ore are mainly oxidative roasting, pressurized oxidation, bacterial oxidation, and alkali. Immersion oxidation method, nitric acid decomposition method, vacuum arsenic removal method, volatile smelting method, isolation roasting method, chemical oxidation method, chlorination method, oxidation of sulfur-containing reagent, and introduction of magnetic field during leaching to enhance leaching and ultrasonic enhanced leaching [5,6] . Among them, there are four kinds of pretreatment methods which have been industrially applied at home and abroad, such as calcination oxidation method, pressure oxidation method, bacterial oxidation method and chemical oxidation method. From the perspectives of technology, economy, and environmental protection, various methods also have the disadvantages of large environmental pollution, high equipment material requirements, large changes in bacterial activity caused by changes in environmental conditions, serious equipment corrosion, high cost, and poor adaptability of ore. In experimental research, gold leaching is significantly promoted by the introduction of a magnetic field or ultrasonic waves during the leaching process. Qiu Tingsheng and other test results show that under the same leaching conditions, the magnetic field enhanced leaching can increase the leaching rate by 33.08% compared with the conventional oxidative leaching. Under the condition of reducing the amount of sodium cyanide and shortening the leaching time, the magnetic field enhanced leaching can still improve the leaching rate. 28.37% [7] . MULTIPURPOSE leaching arsenic while other studies gold silver and manganese ore ultrasonic stressed conditions, to decompose and manganese oxide minerals arsenopyrite containing gold, silver. Experiments show that manganese silver / gold (mass ratio) = 1: 1.3, the concentration of sulfuric acid 0.57mol / L, temperature 95 ℃, high-frequency high-power under the action of ultrasonic conditions, the decomposition rate of the final arsenopyrite 84.9% [8 ] . In addition, some scholars have shown that arsenic is volatilized in the form of elemental arsenic and sulfide when decomposed and calcined under vacuum conditions. Although this treatment can greatly reduce the adverse effects on the environment, it requires high cost. Process equipment, and need to take follow-up air pollution control measures [5,9] . From the development trend of difficult smelting technology in foreign countries, the research and development operating conditions are relatively mild, the reaction speed is fast, the process investment cost and production cost are appropriate, and the pretreatment technology with small environmental pollution is the main development direction [10] . In this paper, the application prospects of phytoremediation are discussed in this paper. Second, the status quo and analysis of plant extraction and alfalfa research With the rapid development of the mining industry, a large number of heavy metal elements enter the soil system, causing serious negative impacts on the ecological environment. Remediation of heavy metal contaminated soil has attracted widespread attention from governments and environmentalists. The traditional methods of soil heavy metal pollution control mainly include: engineering measures and improvement measures. The former refers to the soil replacement method, the cleaning method, the heat treatment method, the electrochemical method, etc., and the latter refers to the addition of modifiers to reduce the harm of pollutants to the ecological environment. Wait. In recent years, with the discovery of hyperaccumulators, the idea of ​​plant extraction and the development of technology, phytoremediation technology that uses super-enriched plants to remove harmful elements from soil and water is obtained with high efficiency, low cost and environmental friendliness. A lot of attention. Phytoremediation techniques can be divided into five types: plant extraction (extraction), plant degradation, plant stabilization (fixation), plant evaporation, and rhizosphere filtration. Plant extraction refers to planting a specific plant on heavy metal-contaminated soil and water, and the plant has special absorption and enrichment ability for specific pollution elements in the matrix, and the plants are harvested and properly treated (such as ashing). After the recovery, the heavy metal can be removed from the soil and water body to achieve the purpose of pollution control and ecological restoration [11] . At present, one of the key points in the research and application of hyperaccumulators is the regulation of hyperaccumulators to enhance the absorption capacity of plants [12] . The approach mainly includes the following two aspects. (1) Adding chemical ligands to improve the bioavailability of heavy metals. Heavy metals in the soil are in a complex equilibrium system, with bioavailable forms accounting for only a small fraction of them. By artificially adding chemical ligands, the balance can be broken and the available form can be increased. Common ligands include artificial chelating agents (such as EDTA, DTPA, etc.) and natural chelating agents (low molecular molecules that can be secreted by plant root exudates). Organic acids such as citric acid, malic acid, etc. [13] . (2) Applying plant nutrition can promote the growth of plants, increase the intensity of root activity, and correspondingly increase the absorption of heavy metals by plants. Robison et al. studied the Ni accumulate plant Berkheya coddii and found that the application of sulfur in the soil can promote the absorption of cobalt and nickel by plants. The content of cobalt and nickel in plants is positively correlated with the addition of sulfur (P<0.01). respectively, can be achieved 1500mg • kg -1 (dry matter), 300 mg • kg -1 (dry matter) [14]; N fertilization produce the same effect, but exert influence on the phosphorus fertilizer little uptake [15]. In addition, studies have shown that root exudates play different roles in phytoremediation of heavy metal contaminated soils. On the one hand, root exudates can activate heavy metal elements in the contaminated area, transforming the fixed state into a plant absorbable state, greatly improving the plant availability of heavy metals, and enhancing the extraction and removal of hyperaccumulators; on the other hand, root exudates are also It can form stable complexes with heavy metals, reduce their mobility in the soil, and play a role in fixation and passivation [11] . For example, plants produce lead phosphate by secreting phosphate and lead in the soil to solidify lead and reduce the toxicity of lead. At present, more than 10 kinds of arsenic super-accumulated (super-enriched) plants have been discovered at home and abroad. They are all ferns and most of them belong to the genus Pteridium. Studies have shown that both Pteris vittata L. and Pteris cretica L. meet the criteria for arsenic hyperaccumulators [16,17] . In addition, under arsenic stress, the root exudates of valerian root were mainly phytic acid and oxalic acid. The amount of two acid secretions was 0.46-1.06 times and 3-5 times higher than that of non-arsenic super-enriched plants, respectively, indicating that root exudates could activate soil arsenic. And effectively transferred to the blade [18] . As an analog of phosphorus, arsenic can pass through the plasma membrane through the phosphorus transport system, and once it enters the cytoplasm, it can compete with phosphorus. For example, it can replace the phosphorus in ATP to form unstable ADP-As, thus cell energy flow. Interference [19] . However, compared with other heavy metals, the physiological response of plants to metal-like arsenic stress is not enough [20] . At present, most of the domestic and foreign researches on phytoremediation of arsenic-contaminated soil and water bodies are carried out with valerian as the main experimental material. In theoretical research, most of them focus on the process of arsenic absorption, transport, enrichment and detoxification. In the practice of plant extraction and repair of arsenic-contaminated soils and water bodies, most studies have focused on factors affecting plant extraction and measures to improve plant extraction efficiency. For example, Tu and Ma (2003) studied the effects of pH, As and P on the growth and absorption of As and P in alfalfa by hydroponic experiments. It was found that the culture medium pH ≤5.21 and maintaining low phosphorus concentration can optimize the growth of alfalfa [21- 23] In the field trial of arsenic-contaminated soil phytoremediation, the Environmental Remediation Laboratory of the Institute of Geographical Sciences and Natural Resources Research of the Chinese Academy of Sciences established a phytoremediation demonstration project for arsenic-contaminated soil in Chenzhou, Hunan Province to explore and test the feasibility of repairing arsenic-contaminated soil by alfalfa. Sex [22] . Valerian is a perennial plant with relatively large biomass. Its tissue arsenic content has the distribution characteristics of pinnae > petiole > rhizome. Valerian can not only enrich a large amount of arsenic in the soil with low arsenic content, but also grow normally in the soil with high arsenic content, enriching a large amount of arsenic. According to Song Shuqiao and other analysis of the biomass of alfalfa in the heavily polluted area of ​​arsenic in Danxian County, Guangxi, the single leaf height can reach 140cm, the fresh weight can reach 33g, the dry weight is 6.6g, in the densely grown place, every square meter. There may be such a blade of about 120 branches, that is, the dry weight per hectare of hectare can reach about 8t, and the amount of arsenic in the upper part is estimated to be 700×10 -6 -800×10 -6 , by harvesting the upper part, each year. About 6 kg of arsenic can be removed from each hectare of soil [24] . Third, the research status and analysis of arsenic conversion In nature, arsenic can exist in many different forms of compounds. The main arsenic found in air, soil, sediment and water is As 2 O 3 or arsenite (As3+), arsenate (As5+), Methyl arsenic acid (MMAA) and dimethyl arsenic acid (DMAA) are mainly present in the form of arsenic betaine (AsB) and arsenic choline (AsC) in seafood. The order of toxicity was As(III)>As(V)>As 2 O 3 >MMAA> DMAA>AsC>AsB [25] . In the environment, the conversion, migration and toxicity of arsenic are largely influenced by the chemical form of arsenic. Arsenic is mainly in the inorganic state in the soil. Under the oxidizing conditions, arsenate is the main component. It mainly exists in the soil in the form of water-soluble arsenic, exchangeable arsenic and fixed arsenic, among which water-soluble arsenic and exchange Arsenic is a soil active arsenic. Their effectiveness is relatively high and they are easily absorbed by plants. However, arsenate is easily fixed by iron, aluminum and other oxides in acidic soil to form fixed arsenic (such as calcium arsenic and iron arsenic). , aluminum type arsenic) is not easily absorbed by organisms and has low toxicity. Arsenite is the main form under reducing conditions, while arsenite has a higher solubility in soil and is more toxic [26] . Due to the special chemical properties of arsenic, the considerations in adsorption, resolution, leaching activation and chemical conversion are more complicated than the general heavy metals. Adsorption and desorption are the main processes affecting the migration, residual and bioavailability of arsenic-containing compounds in soil. Soil texture, mineral composition properties, pH, redox potential (Eh), cation exchange capacity (CEC), anion exchange capacity (AEC) and the properties of competing ions all affect the adsorption process and the morphological distribution of arsenic [27] . Soil pH and redox potential (Eh) are two key factors affecting arsenic activity. Increasing pH or decreasing Eh will increase the concentration of soluble arsenic [25] . OH - or H + directly or indirectly involved in the arsenic adsorption - desorption process, change in pH may facilitate dissociation or association soil surface ligands acid ion protonated, thus affecting the soil surface adsorption and desorption of arsenate ions . A large number of organic and inorganic ions exist in soils and solutions, such as Cl - , SO 4 2- , PO 4 3- and organic ions derived from soil root secretions, plant residue degradation products. These ions affect the adsorption of arsenic in soil to different extents due to competition with arsenic for adsorption sites. The effect of phosphorus on arsenic shows that phosphorus and arsenic can compete with each other in the soil for adsorption points on the soil colloid, and PO 4 3- can accelerate the downward movement of As5+ in the soil column [28] . Zhou Juanjuan and other research results confirmed that the chemical properties of phosphorus and arsenic are similar, there is a competitive adsorption relationship in the soil, increasing the solution phosphorus concentration can reduce the soil's ability to absorb arsenic and increase the desorption of arsenic from the soil. In the case of low phosphorus concentrations, this effect is particularly pronounced, and the desorption of arsenic has a very significant linear correlation with phosphorus concentration [29] . In the rhizosphere soil, phosphorus and arsenic coexisted in the root exudates with more organic acids than when arsenic was added. Root exudates mainly reduce Al-As, Fe-As and Ca-As by competitive adsorption, acidification dissolution, reduction and chelation to activate Al-As, Fe-As [30] . It is generally believed that PO 4 3- or MoO 4 3- can replace the adsorbed arsenic in the soil, and the phosphorus in the soil can also significantly inhibit the adsorption of arsenic by soil (especially clay minerals); but Cl-, SO 4 2- and NO 4 3- has little effect on arsenic adsorption, probably because they differ from the adsorption mechanism of arsenic. 77% of total arsenic in the soil can be replaced with a very high concentration of PO 4 3- solution. The activity of microorganisms in the soil plays an important role in the formation of arsenic compounds. Therefore, microorganisms play an important role in the transformation, migration and toxicity of arsenic in soil. As a result of microbial activity, arsenite As (III) and arsenate As (V) can be oxidized and degraded [31] . Inorganic arsenic compounds can be biomethylated while other microorganisms can demethylate organic arsenic compounds to inorganic states [32] . The rate of arsenic degradation and methylation also depends on soil moisture, soil temperature, the abundance of different forms of arsenic, the number of microorganisms in the soil, and pH, and varies with these conditions [33] . Fourth, the use of alfalfa to extract arsenic removal application prospects China's refractory gold resources reserves are large and scattered, and more than 1,000 tons of such gold have been identified [2] . The use of cost-effective methods to remove gold, such as arsenic and antimony, has become a key factor in improving the extraction efficiency of gold. It is also a hotspot and a difficult point for scientists at home and abroad. The use of arsenic super-accumulated plants can enrich arsenic in large quantities. Arsenic removal from arsenic-bearing gold ore can also be introduced into plants. By harvesting accumulated plants to remove arsenic from gold ore, arsenic can be greatly reduced by gold cyanide leaching. The effect is to greatly increase the cyanide leaching efficiency of gold. As a typical arsenic superaccumulator, Pteris vittata L. is common in southern China, and its biomass is relatively large. Planting such plants in the arsenic-doped gold-bearing area of ​​Yunnan will not cause invasion of exotic species. The arsenic in the gold ore can be quickly removed by harvesting the upper part of the ground and periodically removing the roots, ready for subsequent leaching and gold extraction. The arsenic-containing refractory gold ore often contains a large amount of minerals such as calcium carbonate, magnesite , pyrite, arsenopyrite, orpiment and realgar, and contains a small amount of minerals containing nitrogen, phosphorus and potassium. After grinding, it can be used to grow alfalfa before being heaped by cyanidation. Its composition can meet the demand of calcium and a large number of elements in alfalfa. It is theoretically feasible to plant alfalfa in arsenic-bearing gold ore, and fertilize and activate properly. By the treatment of the control means, the arsenic super-accumulation characteristics of valerian can be exerted, and the extraction and removal efficiency of arsenic can be improved. At present, although there are many studies on the methods of adsorption, analysis and microbial transformation of arsenic in soil, the effective extraction pretreatment is still one of the problems, and from the literature reviewed, it has not been included. Research on plant pretreatment in arsenic gold ore. Regulatory methods applied to water or soil phytoremediation can also be introduced into arsenic-bearing gold ore to test and explore its mechanism. Due to the special chemical properties of arsenic, its considerations in adsorption, resolution, leaching activation and chemical conversion are more complicated than ordinary heavy metals. The differences in the composition of soils and gold deposits, as well as the morphological differences in arsenic in soils and gold deposits, have different effects on the activation of arsenic. They need to be used in gold mines to adjust the pH and redox potential of gold. A comparative study of arsenic activation effects by different reagents. Therefore, the chelating agent commonly used in phytoremediation is used to study the activation of arsenic in gold ore, and the effective activator is screened to increase the biomass and accumulation of valerian, thereby improving the efficiency of arsenic removal. The pre-treatment method for arsenic removal in plants is to reduce the arsenic content of gold ore by using certain plants to absorb arsenic in gold ore. Compared with biological oxidation, high pressure oxidation and roasting, the method has low investment and maintenance cost, small engineering quantity, simple operation and management, no secondary pollution, and good effect on maintaining water and soil and beautifying the landscape. It is an environment. The friendly method can be widely used for pretreatment of cyanidation (heap leaching) of refractory gold ore with high arsenic content. This paper provides a new method and idea for the arsenic removal pretreatment of many arsenic-containing refractory gold ore resources in China. In addition, some tailings after heap leaching still contain more arsenic and gold, which not only causes environmental pollution, but also causes waste of gold. Therefore, this study can also be used for tailings arsenic removal and gold in tailings. Further refinement of the pretreatment. In summary, the arsenic and arsenic pretreatment method has broad application prospects for the ore, concentrate and tailings with high arsenic content in gold smelting. references [1] Liu Siqing, Song Huanbin. Process mineralogy of arsenic-bearing gold ore and its application[J].Journal of Kunming University of Science and Technology,1998,(4):20～21. [2] Yang Tianzu. Precious metallurgy and deep processing of products [M]. Changsha: Central South University Press, 2005. [3] Jiang Guohong, Ouyang Lunzhen, Zhang Yanmin.Experimental study on roasting-cyanide leaching gold process of arsenic-sulfur-high carbon card type gold ore[J].Journal of Hydrometallurgy,2003,22(3):129～132. [4] Ye Guohua, Tong Xiong, Zhang Jie. Research progress on arsenic removal from arsenic-bearing ore [J]. Foreign metal ore dressing , 2006, (3): 20~24~30. [5] Liu Hanqi. Current status and prospects of roasting oxidation of refractory gold ore at home and abroad [J]. Foreign metal ore dressing, 2005, (7): 5~10. [6] Bao Lijun, Wu Guoyuan. Pretreatment of high arsenic sulfur gold ore[J]. Precious Metals, 2003, 24 (3): 61~66. [7] Qiu Tingsheng, Xiong Shuhua, Xia Qing.Experimental study on magnetic field enhanced cyanide leaching of arsenic-containing refractory gold deposits[J].Metal Mine,2004,(12):32～34. [8] Yuan Mingliang, Zhao Guoshen, Qiu Guanzhou. Ultrasonic Strengthening in Simultaneous Leaching of Arsenic Gold and Manganese Silver Deposits[J]. Chinese Journal of Process Engineering, 2003, 3(5): 409~412. [9] VA Luganov, Zhang Xingren, Li Wei. Treatment Process of Arsenic-Containing Gold Ore[J]. Foreign Metal Ore Dressing, 2004, 41(11): 14~18. [10] Tang Qingguo, Shen Shangyue. Non-cyanide leaching of high arsenic gold deposits [J]. Comprehensive Utilization of Mineral Resources, 2003, (2): 16~20. [11] Yan Hongjian, Jiang Xin, Chang Jiang, et al. The role of root exudates in bioremediation of contaminated soils [J]. Ecology, 2004.23(4): 135~139. [12] Wu Zhenghua. Research progress on phytoremediation of heavy metal pollution in soil[J]. Journal of Yancheng Institute of Technology, 2002, (15): 53~57. [13] Weasy S A. Remediation of soils polluted by heavy metals using organic acids and chelating[J].Environmental Technology, 1998, 19(4): 369-379. [14] Robinson BH, Brooks RR, Clothier B E. Soil amendment affecting Nickel and Cobalt uptake by Berkhyea coddii: potential use for phytomining and phytoremediation [J]. Annals of Botany, 1999, 84(6): 689-694. [15] Wang JR, Zhao FJ, Andrew A, et a1. Mechanisms of arsenic hyperaccumulation in Pteris vittata: uptake kinetics, interactions with phosphate. and arsenic speciation [J]. Plant Physiology, 2002.130:1552~1561. [16] Chen Tongbin, Wei Chaoyang, Huang Zechun, et al. Enrichment of arsenic by arsenic and its enrichment characteristics of arsenic[J].Chinese Science Bulletin,2002,47(3):207～210. [17] Wang HB, Ye ZH, Shu WS, et a1. Arsenic uptake and accumulation in fern components growing at arsenic-contaminated sites of Southem China: Field surveys[J]. International Journal of Phytoremediation,2006,(8):1 ~11. [18] Wang HB, Wong MH, Lan CY, et a1. Uptake and accumulation of arsenic by 1l Pteris taxa from southern China[J]. Environmental Pollutian, 2007, (145): 225~233. [19] Meharg AA, Macnair MR. Suppression of the high affinity phosphate uptake system: a mechanism of arsenate tolerance in Holcus lanatus L [J]. Journal of Experimental Botany, 1992, 43(4): 519-524. [20] Hartley Whitaker J, Ainsworth G, Meharg AA. Copper and arsenate induced oxidative stress in Holcus lanatus L. clones with differential sensitivitv [J]. Plant, Cell and Environment, 2001, 24: 713-722. [21] Tu C, Ma LQ. Effects of arsenic concentrations and forms on arsenic uptake by the hyperaccumulator ladder brake [J]. Journal of Environmental Quality, 2002, 31: 641-647. [22] Liao Xiaoyong, Chen Tongbin, Xie Hua, et al. Effect of phosphate fertilizer on phytoremediation efficiency of arsenic-contaminated soil: a case study in the field[J]. Journal of Environmental Science, 2004, 24(3): 455~462. [23] Chen TB, Wei CY, Huang ZC, et a1. Arsenic hyperaccumulator Pteris vittata L. and its arsenic accumulation [J]. Chinese Science Bulletin, 2002, 47: 902-905. [24] Song Shuqiao, Zhou Yongzhang, Zhou Bi, et al. Characteristics of soil arsenic pollution and phytoremediation[J].Tropical Geography,2004,24(1):6～9. [25] Zhang X, Cornelis R, DE Kimpe J, et a1. Speciation of toxicologically important arsenic species human serum by Liquid Chromatography-hydride generation atomic absorption spectrometry [J]. Journal of Analytical Atomic Spectrometry, 1996, 11: 1075～1079 . [26] Li Daolin, Cheng Lei. Morphological distribution of arsenic in soil and biological effects of green vegetables[J]. Journal of Anhui Agricultural University, 2000, 27(2): 131~134. [27] Chen Tongbin. Relationship between arsenic in soil solution and rice hopping effect[J].Acta Ecologica Sinica,1996,16(2):147～153. [28] Liang Yuefan. Transformation of arsenic in soil and its biological effects [D]. Huazhong Agricultural University, 2007, 8~12. [29] Zhou Juanjuan, Gao Chao, Li Zhongpei, et al. Effects of phosphorus on soil As(V) fixation and activation[J]. Soil, 2005, 37(6): 645~648. [30] Zhang Guangli, Song Guangbiao. Morphological distribution of inorganic arsenic in roots under the influence of phosphorus and its effects on rice growth[J]. Journal of Soil Science, 2002, 39(1): 23~28. [31] Woolson E A. Fate of arsenicals in different environmental substrates [J]. Environmental Health Perspectives, 1977, 19: 73-81. [32] Yoshiki Sohrin, Masakazu Matsui, Munetsugu Kawashima, et a1. Arsenic biogeochemistry affected by eutrophication in Lake Biwa, Japan [J]. Environment Science Technology, 1997, 31: 2712~2720. [33] William R Cullen, Kenneth J Reimer. Arsenic speciation in the environment [J]. Chemical Reviews, 1989, 89(4): 713-764. (Author: Wanghai Juan Ninh Binh Xiaoqing Qing Department: College of Environmental Science and Engineering, Kunming University, Kunming) (Author: Tangxing into the unit: China Gold Group Co., Ltd., Guizhou, Guiyang) (Author: Zhang Zebiao Unit: Institute of Materials and Metallurgical Engineering, Kunming University, Kunming) Reflective Safety Vest,High Visibility Safety Vest,100% Polyester Reflective Safety Vest,Reflective Safety Vest For Railway Ningbo Deying Reflective Products Co.,Ltd , https://www.deyingsafe.com