Feasibility analysis of localization of 2×400kt/a pyrite-based sulphuric acid plant

Abstract: The Status of the Large Pyrite localization for copper ore sand Dongguashan high magnetic pyrite mineral content, fine granularity byproduct sulfur fine features, of 2 × 400 kt / a pyrite The process of the plant, the "three wastes" treatment, the choice of system configuration and the localization of key equipment such as boiling furnace, waste heat boiler, electrostatic precipitator, drying tower, absorption tower, converter, and converter, and analyze the possible problems. And put forward suggestions for the localization of large-scale pyrites in China.

Key words: sulfur concentrate; sulfuric acid production; large-scale; localization; feasibility

CLC number: TQ111. 14 Document code: B Article ID: 1002-1507 (2006) 02-0018-04

Copper, Tongling Nonferrous Metal (Group) Company-owned Copper Company Limited are Dongguashan copper ore copper are Copper Co. mine primarily stamina, project estimates a total investment 1.996 billion yuan, was put into trial in October 2004 Production, after production, copper concentrate can be produced about 35kt / a, by-product sulfur concentrate is about 1000kt / a, iron concentrate is more than 150kt / a, by-product sulfur concentrate contains 48.29% of magnetic pyrite. In view of the fact that the ω(Fe) in the by-product sulfur concentrate is as high as 54.63%, the ω(Fe) in the slag after roasting can reach 62% or more, and the slag can be used to make the iron oxide pellet as the charge for the blast furnace ironmaking in the steel industry. It not only solves the pollution caused by waste residue storage to the environment, but also greatly increases the added value of the products. Tongdu Copper Co., Ltd. decided to build a 800kt/a sulfuric acid project in two phases, each with a scale of 400kt/a.

In view of the fact that the largest scale of pyrite sulphuric acid plant at home and abroad is only 400 kt / a, considering the high content and fine grain size of the sulphur fine sand sulphur iron ore in the Dongguashan copper mine, the process selection and localization of the sulphuric acid plant are carried out. analysis.

I. Current status of large-scale pyrite-based sulphuric acid plant

With the improvement of structural materials, the continuous improvement of acid-making technology, the improvement of the production intensity of single equipment, and the optimization of equipment investment and production cost, sulfuric acid plants are continuously developing in the direction of single-series large-scale. At present, the world's largest single series of sulfuric acid is the 4400t/d device of Anaconda Company of Australia. The largest single series of smelting flue gas is the 3800t/d device of Kennecott, Utah, USA. The largest scale of pyrite-based acid series It is the 1200t/d device of Guizhou Hongfu Industrial Company. The development of China's pyrite sulphuric acid manager has gradually formed a large overall scale. Since the 1980s, a large-scale installation has been completed and put into production using imported technology. The main large-scale pyrite-based equipment in China is shown in Table 1.

Table 1 China's major large-scale pyrite plant

Second, process technology and system configuration options

(1) Process technology selection

1, the process

The 2×400 kt/a sulphuric acid plant is intended to adopt a mature “boil roasting, pickling purification, two-turn two-suction” process. The high-temperature sulfur dioxide flue gas produced by the pyrite boiling roasting is recovered by the waste heat boiler, wherein the high-temperature heat energy generates superheated steam, and then the cyclone dust collector and the electric precipitator are removed to the purification process to remove dust, harmful impurities and cool in the flue gas, and the purification is powered. The wave scrubber is packed with a packed tower and a two-stage electric mist eliminator; the flue gas is then subjected to a drying and conversion process, and the IIII-IVII heat exchange process is used for the conversion. The setting of the power wave scrubber is mainly to consider the effect of enhancing the washing effect of the purifying process on the dust. The whole set of equipment is produced by DCS system, which can automatically monitor, control and alarm a series of processes such as process parameters, production equipment, electrical instrument operation and parking.

2, "three wastes" treatment

The slag (ω) of the sulphur concentrate after roasting can reach 62% or more, and can be directly used to make iron oxide pellets as raw materials for blast furnace ironmaking. Therefore, there is basically no waste slag emission during production. The two-rotation and two-suction process and the imported catalyst ensure that the conversion rate is greater than 99.8%, and the SO ₂ in the exhaust gas reaches the standard discharge. The acidic waste water discharged from the purification process is neutralized by limestone to form gypsum , and then mixed with the scene water in various places, neutralized by lime milk, filtered by membrane, and discharged to the standard at night. The neutralized slag is dehydrated by a filter press and sent to the yard for filling. Buried.

(two) system configuration selection

Compared with other raw material acid-making devices, the limitation of the increase in the scale of the pyrite-based sulphuric acid plant is mainly in the boiling furnace. To solve the problem of large-scale pyrite-based mineral acid plant, the problem of the matching between the baking process and the acid-making process must first be solved. The scale of the large-scale pyrite sulphuric acid plant that has been put into operation in China is less than 300kt/a. The design adopts one set of roasting system, one set of acid-making system (commonly known as “one head and one tail”, the same below), and the design of scale up to 400kt/a adopts one set. The roasting system is equipped with one set of acid production system or two sets of roasting system with one set of acid production system (commonly known as "two heads and one tail"). 2 system configuration has production examples in China, each design has advantages and disadvantages, depending on the specific circumstances. Taking into account various factors, the 2×400 kt/a sulphuric acid plant is intended to use a “one-to-one” system configuration.

Third, the feasibility of localization and possible problems

(1) Feasibility of process technology

In the past 10 years, a large number of large-scale pyrite sulphuric acid plants have been built in China. The design of major process technologies is shown in Table 1. In the large-scale pyrite sulphuric acid plant that has been put into operation in China, the key technologies and most of the equipment are basically dependent on imports. The domestic design is only after the basic design of foreign companies. Through the digestion and absorption of imported technologies, the gap between the design and foreign sulfuric acid design technology has been greatly reduced, and the localized design of large-scale sulfuric acid plants has gradually become a reality. Such as Tongling ammonium phosphate plant 200kt / a pyrite sulphuric acid plant, Jinlong company 375kt / a smelting flue gas sulphuric acid plant, Shandong Hongri company 400kt / a sulphur sulphuric acid plant, etc., all or most of the domestic design, Process technology and economic indicators are good. At the same time, the localization design of Jiangxi Yongping 400kt/a pyrite sulphuric acid plant and Yunnan 600~800kt/a sulphur sulphuric acid plant is also underway, and the localization of large pyrite sulphuric acid plant is feasible.

(II) Feasibility of large-scale design of major equipment

The technical difficulty of large-scale sulphuric acid plant is that the large-scale of some equipment will bring difficulties in structural design and even distribution of fluids. If the above-mentioned limits are exceeded, construction investment and material consumption will increase, which will affect the scale efficiency of the equipment. For the pyrite sulphuric acid plant, the links that may affect the large-scale equipment are mainly reflected in the following key equipment.

1. Boiling furnace

The world's largest scale of sulfur and smelting flue gas has greatly exceeded the acidity of pyrite. One of the main reasons is that the large-scale design of the pyrite-based acid boiling furnace has too much roasting area, which brings a huge volume structure. A series of complex problems such as the design and uniformity of gas distribution. It has been designed to put into boiling furnace, foreign calcined largest Spanish Almagrera Sa 910t / d acid plant roaster 123M ^2; largest Northwest lead zinc smelter and 109m zinc concentrate Zhuzhou Smelter ² fluidized bed furnace, The area of ​​pyrite-based acid boiling furnace is currently the largest 60m ² boiling furnace of Guizhou Hongfu Industrial Company (volume about 2500m ³ ). These boiling furnaces that have been put into operation in China are all based on the introduction, and the domestic design department has completed the detailed design. Through the accumulation of large-scale boiling furnace design and production practices, it provides technical guarantee for the localized design of large-scale equipment.

2, waste heat boiler

At present, pyrite-based acid waste heat boilers have three forms: natural circulation, mixed circulation, and forced circulation. In view of the large-scale single-acid plant and the design and operation characteristics of the pyrite-based acid waste heat boiler, the steam-water cycle of the boiler is mainly forced circulation. Among them, the following three types of furnaces can be selected, namely, a W-type flue gas flow type with a pre-diffusion settling chamber, a W-type with a cooling flue type, and a horizontal flushing type with a straight-flow horizontal flue gas flow. In foreign countries, Germany Luqi Company and Finland Oslo Company mostly use straight-flow horizontal flue gas lateral flushing type waste heat boiler. China introduced this technology in the late 1980s and has the ability to design and manufacture it by itself. This kind of boiler is also used in the 400kt/a pyrite sulphuric acid plant of Guihong Hongfu Industrial Co., Ltd., and the effect is very good.

3, electric precipitator

Like the waste heat boiler, China has successfully designed and produced an electrostatic precipitator for 200kt/a pyrite sulphuric acid plant through digestion and absorption of imported technology. The electrostatic precipitator of large pyrite sulphuric acid plant can be locally localized. .

4, other equipment

Other equipment mainly includes three types of equipment: drying tower, absorption tower and converter. At present, the design of domestically produced sulphur and smelting flue gas sulphuric acid plants above 400 kt/a is basically at a mature stage, such as the Yunnan three-ring kt/a sulphur-based sulphuric acid plant designed by Donghua Engineering Technology Co., Ltd., designed by Nanchang Nonferrous Metals Design and Research Institute. The smelting flue gas sulphuric acid plants of Guixi, Jinlong and other companies, the design indexes (including the material selection) of these units for dry suction tower converters and converters have approached or exceeded the advanced level in foreign countries, indicating that China has large-scale equipment design. ability. Moreover, most of the large-scale sulphuric acid devices that have been put into operation in China are manufactured and installed in China, and the use effect is good.

(3) Possible problems

In summary, China has basically been able to independently complete the design and construction of large-scale pyrite sulphuric acid plants. However, for the particularity of the sulphur concentrate in the winter melon mountain, the sulphuric acid plant still has certain difficulties and risks in adopting the “one-to-one” domestic design, mainly in the following two aspects.

1. The content of magnetic pyrite is too high. The content of magnetic pyrite in the fine sand of the Dongguashan Copper Mine (mass fraction) reached 49.29%. The excessive content of the magnetic pyrite will affect the desulfurization effect, thus affecting the further comprehensive utilization of the sintered pellets. The phase analysis of sulfur in the sulfur concentrate is shown in Table 2.

Table 2 Results of phase analysis of sulphur concentrate in Dongguashan Copper Mine

2. The fine grain of sulfur concentrate is fine. The particle size is less than 0.045mm and the particle size reaches 78.16% (see Table 3 for details). Due to the finer particle size, the calcination strength and gas velocity selected for the design are unlikely to be too large, thereby greatly increasing the boiling furnace bed area. According to the experimental prediction, the boiling bed area of ​​400kt/a plant needs to reach 138m ² , while the current boiling area of ​​400kt/a pyrite sulphuric acid plant in China is only 60 m ² , and there is a certain risk in localized design.

table 3

4. Suggestions on the localization of large-scale pyrites in China

The pyrite-based sulphuric acid plant is developing in a large-scale hufangxiang, and it is necessary to solve the relationship between localization and high operation rate, large-scale and technical reliability. The localization of large-scale pyrite sulphuric acid plant in China is necessary and feasible. It is necessary to design an advanced and reliable large-scale sulphuric acid plant in combination with the actual situation, while saving investment and reducing costs, and exerting scale and comprehensive utilization efficiency.

(1) The determination of the scale of the equipment should be based on technical reliability. The limitation of the large-scale pyrite-based sulphuric acid plant is on the boiling furnace, waste heat boiler and electrostatic precipitator of the roasting system, especially the boiling furnace. Therefore, it is necessary to actively digest foreign advanced design and equipment processing technology, and combine the mature design technology of the domestic 200-250 kt/a boiler boiling furnace to complete the localization of a single series of 400kt/a pyrite sulphuric acid plant. For the 400-500 kt / a pyrite sulphuric acid plant, it can be designed as a two-burning system plus one set of acid-making system configuration, so that the investment is relatively small and the reliability is relatively high. Of course, it is also feasible to choose one set of roasting system with one set of acid-making equipment, but it must bear the cost of technology introduction and investment, and the risk of large-scale boiling furnace design.

(2) Localized design with high starting point and partial introduction of localized rain. In view of the difficulties in the large-scale production of pyrite-based sulphuric acid plants and the advanced technologies owned by foreign countries, it is necessary to combine localization with imported technologies, and the introduction of technologies needs to be advanced, and will not be eliminated within 10 to 20 years.

(3) Increasing the granularity of technical research on difficult points and the digestion and absorption of foreign technology. In recent years, although China has introduced a lot of foreign technology, the key technology has always been difficult to grasp due to the confidentiality of foreign companies, and there is no targeted research in China. Therefore, while increasing the intensity of difficult technical research, we must actively absorb and absorb imported foreign technology.

Feasibility analysis of localization of 2×400kt/a sulphuric

(Tongling Non-ferrous Metal Co., Ltd., Tongling, Anhui, 244000, China)

Abstract: The present situation of localization of large-scale sulphuric acid plants based on pyrite is introduced.According to the features of high concentration magnetic pyrite and fine particle size of Dongguashan byproduct pyrite, process arrangement, "three wastes" disposal and localization of key Equipment such as fluidized bed roaster, waste heat boiler, electrostatic precipitator, drying and absorption towers and converter are analyzed.Possible problems are pointed and some recommendations about localization of large-scale sulphuric acid plants based on pyrite are made.

Key words:pyrite;sulphuric acid production;large-scale plants;localization;feasibility

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