Sustainable analysis of domestic production of sulfuric acid plants using pyrite

Abstract: This article introduces the current situation of domestic production of large-scale sulfuric acid equipment from pyrite in China. In response to the high content and fine particle size of magnetite in the by-product sulfur concentrate of Dongguashan Copper Mine, it is recommended to × Analyze the process flow, “three wastes” treatment, selection of system equipment, and localization of key equipment such as jubilant furnace, waste heat boiler, electrostatic precipitator, drying tower, absorption tower, converter, and converter for a 400 kt/a sulfuric acid plant using pyrite, and point out potential problems; And propose proposals for the localization of large-scale sulfuric acid production from pyrite in China.
Keywords: sulfur refined sand; Production of sulfuric acid; Large scale; Localization; feasibility
Chinese Library Classification Number: TQ111. 14 Literature Identification Code: B Article Number: 1002-1507 (2006) 02-0018-04
The primary potential mine of Tongdu Copper Industry Co., Ltd., a subsidiary of Tongling Nonferrous Metals (Group) Company, is Dongguashan c110 c11000 copper Mine and Tongdu Copper Industry Co., Ltd. The estimated total investment for the project is 1.996 billion yuan. It was put into trial production in October 2004 and can produce about 35kt/a of copper concentrate, 1000kt/a of by-product sulfur concentrate, and over 150kt/a of iron concentrate. The by-product sulfur concentrate contains 48.29% magnetite. Considering the by-product of sulfur fine sand ω (Fe) up to 54.63%, in the calcined slag ω (Fe) can reach over 62%, and the slag can be used to produce iron oxide pellets as the burden for blast furnace ironmaking in the steel industry. This not only reduces the pollution caused by waste slag stacking to the environment, but also greatly improves the added value of the product. Tongdu Copper Industry Co., Ltd. has decided to build an 800kt/a sulfuric acid project in two phases, with each phase’s equipment planned to be 400kt/a.
Considering that the maximum planned capacity of domestic and international sulfuric acid production equipment using pyrite is only 400kt/a, and considering the high content and fine particle size of magnetite from Dongguashan Copper Mine, the process selection and localization of sulfuric acid production equipment are analyzed.
1、 Current status of large-scale sulfuric acid production equipment from pyrite
With the improvement of structural materials, continuous progress in acid making skills, progress in the production intensity of monomer equipment, and the requirements for optimizing equipment investment and production costs, sulfuric acid equipment is constantly moving towards the direction of large-scale single series production. Currently, the world’s largest planned acid production single series is the 4400t/d equipment of Anaconda Company in Australia, the 3800t/d equipment of Kennecott, Utah, USA, and the 1200t/d equipment of Guizhou Hongfu Industrial product Company in China. After years of development, China’s pyrite based sulfuric acid production company has gradually formed a larger overall plan. Since the 1980s, a large scale of equipment has been built and put into operation using imported skills. The primary large-scale pyrite based equipment in China is shown in Table 1.
Guizhou Hongfu Industrial Company
Huanteng furnace, waste heat boiler, cyclone dust collector, electric dust collector, “air filling room electric” purification, “2+2” two rotation and two suction
German Luqi Roasting, Japanese Mitsubishi Heavy Industries Purification Skills, and specific plans of East China Engineering Technology Co., Ltd; In 2001, it was changed to mixed firing
Guangxi Luzhai Fertilizer Company
Huanteng furnace, waste heat boiler, cyclone dust collector, electric dust collector, “bubble electric” purification, “2+2” two rotation and two suction
Roasting skills from Doyle Company in the United States, acid production skills from Silisamon in Italy, skills from SHG Company in Germany for waste heat boilers, and skills from Luchi Electric Precipitator (manufactured by Hyundai Company in South Korea). Specific planning from Nanhua Planning Institute
Hubei Huangmailing Chemical Company
Huanteng furnace, waste heat boiler, cyclone dust collector, electric dust collector, “air filling electric” purification, “3+1” two turn two suction
Swedish Politon roasting skills, American Monsanto acid making skills, and specific plans of China’s Fifth Ring Chemical Engineering Company
Yunnan Yunfeng Company
Huanteng furnace, waste heat boiler, cyclone dust collector, electric dust collector, “air filling room electric” purification, “3+1” two turn two suction
German Rucci roasting skills, planned by the Nanhua Planning Institute
Tongling Ammonium Phosphate Plant
Huanteng furnace, waste heat boiler, cyclone dust collector, electric dust collector, “air filling room electric” purification, “3+1” two turn two suction
Kemidi Company’s stainless steel converter in Canada, planned by Donghua Engineering Technology Co., Ltd
Nanjing Chemical Industry Co., Ltd
Huanteng furnace, waste heat boiler, cyclone dust collector, electric dust collector, “air filling room electric” purification, “3+1” two turn two suction
German Rucci roasting skills, planned by the Nanhua Planning Institute
2、 Selection of process skills and system equipment
（1） Selection of process skills
1. Process flow
two × The 400kt/a sulfuric acid equipment is planned to use the experienced “jubilant roasting, acid washing purification, two conversion and two suction” process flow. The high-temperature sulfur dioxide flue gas generated by the jubilant roasting of pyrite is recovered by the waste heat boiler, during which the high-temperature heat energy is generated into superheated steam. It then enters the cyclone dust collector and electric dust collector to remove dust and harmful impurities from the flue gas and cool down in the purification process. The purification is equipped with a power wave scrubber, a filling tower, and a two-stage electric mist eliminator; The flue gas then enters the drying and conversion process, and the conversion uses the III-IV-II heat exchange process. The primary consideration for setting up a power wave scrubber is to enhance the cleaning effect of the purification process on dust. The entire equipment is operated using a DCS system, which can actively monitor, control, adjust, and alarm interlocking a series of processes such as process parameters, production equipment, electrical appearance and working conditions, and parking as needed.
2. Treatment of “Three Wastes”
The calcined slag of sulfur concentrate sand ω (Fe) can reach over 62% and can be directly used to produce iron oxide pellets as raw materials for blast furnace ironmaking, thus there is no waste residue discharge during production. Select the two turn two suction process and imported catalyst to ensure a conversion rate of more than 99.8% and qualified emission of SO2 in the tail gas. The acidic wastewater discharged from the purification process is neutralized by limestone to form gypsum, which is then mixed with the surrounding water. After being neutralized by lime milk and treated with membrane filtration, it is discharged after passing the night cleaning process. The neutralized residue is dehydrated by a filter press and sent to the landfill for landfill.
（2） System equipment selection
Compared with other material based acid making equipment, the main limitation of the increased planning of pyrite based acid making equipment lies in the jubilant furnace. To address the problem of large-scale pyrite based acid making equipment, the first step is to address the matching problem between the roasting process and the acid making process. The large-scale sulfuric acid production equipment that has been put into operation in China is planned to use one roasting system and one acid production system (commonly known as “one head, one tail”, the same below) for those with a capacity of less than 300kt/a, and one roasting system with one acid production system or two roasting systems with one acid production system (commonly known as “two ends, one tail”) for those with a capacity of 400kt/a. There are production examples of 2-system equipment in China, and each planning scheme has its advantages and disadvantages, which depend on the specific situation. Summarize and consider various factors, 2 × The 400kt/a sulfuric acid equipment is planned to be equipped with a “one head, one tail” system.
3、 The feasibility and potential problems of localization
（1） Feasibility of process skills
Over the past decade, China has successively built a batch of large-scale sulfuric acid production equipment using pyrite, and the primary process skill planning status is shown in Table 1. In the large-scale sulfuric acid production equipment that has been put into operation in China, the key skills and most of the equipment rely solely on imports. In China, specific planning is only carried out after foreign companies provide basic planning. Through the digestion and absorption of introduced skills, the distance between foreign sulfuric acid planning skills has been greatly reduced, making the localization planning of large-scale sulfuric acid equipment gradually become practical. For example, the 200kt/a sulfuric acid production equipment from pyrite at Tongling Ammonium Phosphate Plant, the 375kt/a sulfuric acid production equipment from smelting flue gas at Jinlong Company, and the 400kt/a sulfuric acid production equipment at Shandong Hongri Company have all or most of them selected localization planning, with outstanding process skills and economic goals. Together, the localization planning for the 400kt/a sulfuric acid production equipment from Yongping, Jiangxi and the 600-800kt/a sulfuric acid production equipment from Yunnan is also underway. The localization of large-scale sulfuric acid production equipment from pyrite is feasible.
（2） Feasibility of large-scale planning for primary equipment
The technical difficulty of large-scale sulfuric acid equipment lies in the difficulty of structural planning and uniform fluid dispersion caused by certain equipment, such as exceeding certain limits, which will increase construction investment and material usage, and affect the planning efficiency of the equipment. Regarding the sulfuric acid production equipment from pyrite, the key factors that may affect the equipment’s large-scale production are mainly reflected in the following key equipment.
1. Jubilant furnace
The world’s largest plan for sulfuric acid production from smelting flue gas has greatly surpassed that of sulfuric acid production from pyrite. One of the primary reasons for this is that the large-scale planning of the pyrite based sulfuric acid production jubilant furnace has a large roasting area, which has brought about a series of disorderly problems such as the planning of huge volume structures and the uniformity of gas distribution. Among the planned and put into operation jubilant furnaces, the largest roasting area in foreign countries is the 123m2 jubilant furnace in the 910t/d acid production equipment of Almagrera S.a in Spain; The largest zinc concentrate jubilant furnace in China is located in the Northwest Lead Zinc Smelter and Zhuzhou Smelter, with an area of 109m2. The area of the pyrite based acid production jubilant furnace is now the largest in Guizhou Hongfu Industrial Company’s 60m2 jubilant furnace (with a volume of approximately 2500m3). The jubilant furnaces that have been put into operation in China are all based on the introduction, and specific plans have been completed in the domestic planning section. Through the accumulation of planning and production practices for large-scale jubilation furnaces, skills have been provided to ensure the localization planning of large-scale equipment.
2. Waste heat boiler
Nowadays, there are three methods for waste heat boilers in sulfuric acid production from pyrite: natural circulation, mixed circulation, and forced circulation. Given the large-scale production of single series acid plants and the planning and working characteristics of waste heat boilers for pyrite acid production, the steam water circulation of the boiler is mainly forced circulation. During this period, there are three types of furnaces that can be selected, namely the W-type flue gas flow with a pre dispersed settling chamber, the W-type with a cooling flue, and the straight horizontal flue gas flow transverse erosion type. In foreign countries, German company Ruch and Finnish company Oslon mostly choose through horizontal flue gas flow horizontal flushing waste heat boilers. China introduced this skill in the late 1980s and now has the ability to plan and manufacture independently. This type of boiler is also used in the 400kt/a sulfuric acid production equipment of Valuable Hongfu Industrial Company, which works well.
3. Electrostatic precipitator
Similar to waste heat boilers, after digesting and absorbing the introduced skills, China has successfully planned and manufactured an electrostatic precipitator for a 200kt/a pyrite based sulfuric acid plant. The electrostatic precipitator for large-scale pyrite based sulfuric acid plants can be fully localized.
4. Other equipment
Other equipment mainly includes three categories of equipment: drying tower, absorption tower, and converter. At present, the planning of domestically produced sulfuric acid equipment with a capacity of over 400kt/a and smelting flue gas is fundamentally in the mature stage. For example, the Yunnan Third Ring kt/a sulfuric acid equipment planned by Donghua Engineering Technology Co., Ltd., and the smelting flue gas sulfuric acid equipment planned by companies such as Guixi and Jinlong planned by Nanchang Nonferrous Metallurgical Planning and Research Institute have all approached or surpassed the advanced level of foreign countries in terms of the planning goals of dry absorption tower and converter (including the selection of raw materials), Clarify that China has the planning talent for large-scale equipment. And the vast majority of the large-scale acid production equipment that has been put into operation in China are domestically manufactured, with outstanding application effects.
（3） Possible issues
In summary, China has independently completed the planning and construction of large-scale sulfuric acid production equipment based on its nature. However, regarding the particularity of Dongguashan industrial and mining sulfur fine sand, there are still certain difficulties and dangers in selecting a “one head, one tail” localization plan for acid production equipment, mainly manifested in the following two aspects.
1. The content of magnetite is too high. The content (mass fraction) of magnetite in the sulfur concentrate of Dongguashan Copper Mine reaches 49.29%. If the content of magnetite is too high, it will affect the desulfurization effect, and then further induce and utilize the sintered slag pellets.
2. Sulfur fine sand with fine particle size. The particle size smaller than 0.045mm reaches 78.16% (see Table 3 for specific conditions). Due to the finer particle size, the planned roasting intensity and gas velocity may not be too large, and then the area of the jubilant furnace bed is greatly increased. According to experimental speculation, the area of the 400 kt/a equipment’s jubilation bed needs to reach 138 square meters. However, currently, the largest jubilation furnace area of the 400 kt/a pyrite based sulfuric acid production equipment in China is only 60 square meters, which poses certain risks in localization planning.
4、 Proposition for the localization of large-scale sulfuric acid production from pyrite in China
It is necessary to handle the relationship between localization and high work rate, large-scale production, and skill reliability, as the sulfuric acid production equipment from pyrite is being developed in large-scale Harbin. It is necessary and feasible for China’s large-scale sulfuric acid production equipment to be domestically produced. It is necessary to plan advanced and reliable large-scale sulfuric acid production equipment based on actual conditions, while saving investment and reducing costs, to fully utilize the planned and summarized die casting high power lamp aluminum alloy hook.
（1） Equipment planning must indeed be based on skill reliability. The limitation of large-scale sulfuric acid production equipment from pyrite lies in the jubilant furnace, waste heat boiler, and electrostatic precipitator of the roasting system, especially the jubilant furnace. Therefore, it is necessary to actively digest advanced planning and equipment processing skills from abroad, and combine them with the experienced planning skills of domestic 200~250kt/a equipment jubilation furnaces to complete the localization of single series of 400kt/a or above pyrite based sulfuric acid production equipment in advance. Regarding the 400~500kt/a sulfuric acid production equipment from pyrite, it can be planned to include two sets of roasting systems and one set of acid production system, which has relatively less investment and higher reliability. Of course, it is also feasible to choose one roasting system and one acid production equipment, but it is necessary to bear the resulting skill introduction and investment costs, as well as the danger of large-scale jubilation furnace planning.
（2） High starting point localization planning, combined with the introduction of localized rain parts. In view of the difficulties in the large-scale production of pyrite based sulphuric acid equipment and the advanced skills available abroad, it is necessary to combine localization with the introduction of skills. The introduction of skills should be progressiveness and should not fall behind in screening within 10 to 20 years.
（3） Increase the granularity of discussion on difficult skills and the digestion and absorption of foreign skills. In recent years, although China has introduced many foreign skills, key skills have been difficult to grasp due to the confidentiality of foreign companies, and there is a lack of targeted research in China. Therefore, while increasing efforts to tackle difficult skills, it is also necessary to actively digest and absorb imported foreign skills.