Method for preparation of sulfuric acid and combined production of fine flour iron through calcination of coal-derived pyrite in presence of oxygen-rich air

Abstract

The invention provides a method for preparation of sulfuric acid and combined production of fine flour iron through calcination of coal-derived pyrite in presence of oxygen-rich air, which belongs to the technical field of resource utilization of coal-containing pyrite. The method comprises the following steps: delivering pretreated coal-derived pyrite and oxygen-rich air into a fluidized bed roaster for calcination, carrying out cooling and dust collecting on high temperature furnace gas through a water pipe, a waste heat boiler and the like, carrying out cooling and demisting on furnace gasby using a one-stage dynawave scrubber--a packed scrubbing column--a two-stage electric mist collector, supplementing a proper amount of common air before furnace gas enters into a drying column, controlling the volume ratio of oxygen to sulfur dioxide in gas in a converter to be greater than 0.8, carrying out reforming and absorption two times after gas enters into a reforming and absorption system, discharging tail gas when the tail gas reaches the standard, and recovering heat energy of furnace gas, slag and dust, furnace gas treated by an electric dust collector, reforming gas of a reforming system and cyclic acid of an absorption system for by-production of middle and low pressure steam. According to the invention, high-level and middle-level heat energy produced in the process of production of sulfuric acid is fully utilized, and the resource of dilute sulfuric acid is recycled; therefore, the advantages of small production investment, low production cost, a high recovery rate of waste heat, clean production and no pollution in production of sulfuric acid are realized.

Description

technical field [0001] The invention belongs to the technical field of resource utilization of coal-bearing pyrite, and in particular relates to a method for roasting coal-based pyrite to co-produce iron fine powder with sulfuric acid. technical background [0002] Coal-measure pyrite, also known as coal-bearing (carbon) pyrite, is an important sulfur resource. At present, the domestic coal-measure pyrite reserves that are symbiotic and associated with coal are about 1.64 billion tons, accounting for more than 50% of the total pyrite reserves. Recently, large-scale coal-measure pyrite mines with nearly 100 million tons of reserves have been proven in southern Sichuan and Guangxi . After screening, washing, and flotation, the sulfur content of coal-measure pyrite can reach more than 45%, the low carbon content is below 5%, and the high carbon content can reach 12% to 20%. Pyrite is not widely used in industry, it is mainly used as raw material for sulfuric acid production, ...

AI Technical Summary

Problems solved by technology

[0003] Existing high-carbon pyrites can reduce the carbon content to less than 5% by adopting carbon reduction and sulfur extraction processes (such as reverse flotation carbon removal-positive flotation sulfur extraction-selective flocculation process), but the process is complicated and production High cost, large discharge of waste water and waste residue, and a large amount of carbon resources are discarded by flotation, serious waste of resources

It is difficult to meet the needs of large-scale industrial production of coal-measure pyrite

[0004] The existing sulfuric acid production process of pyrite ore roasting has higher requirements on the carbon content of pyrite ore, and generally requires that the mass fraction ratio of carbon to sulfur should not exceed 0.2, because when roasting, the carbon content in pyrite ore increases by 1%, and the oxygen consumption Increased by 2.67%, the higher the carbon-sulfur mass fraction ratio, the more unfavorable for acid production

The following five problems exist in the acid production of high-carbon pyrite ore: ① The oxygen consumption is large, and the corresponding increase in the introduction of "inert" gas N 2 number of components, and roasting produces CO 2 components, which will reduce the concentration of sulfur dioxide in the furnace gas, which is not conducive to the self-heating balance of the conversion system; and the "inert" gas N 2 and CO 2 A large amount of heat energy is taken away from the acid system, and the efficiency of heat energy recovery is reduced

② Both sulfur and carbon combustion consume oxygen. Once the oxygen content of the fluidized fluidized furnace is insufficiently controlled, it is easy to cause incomplete combustion of sulfur and carbon to produce sublimated sulfur and carbon monoxide. After the sublimated sulfur and carbon monoxide are brought into the follow-up system, sulfur will accumulate in the dust removal and purification equipment , carbon monoxide will be burned in waste heat boilers and converters, seriously affecting process production

④ "inert" component in acid gas - N 2 and CO 2 The volume is large, the gas flux per unit of sulfuric acid product is large, and the pyrite roasting, waste heat recovery, gas purification, conversion and dry suction equipment are too large, which is not conducive to large-scale and economical production

Chinese patents CN94110617.9, CN99112067.1, and CN200410079527.4 respectively disclose methods such as roasting pyrite with oxygen-enriched air or pure oxygen, and catalytic oxidation of coal-based pyrite to produce polyiron and iron yellow, but no coal is found in the Chinese patent Technical disclosure of sulfuric acid co-production of iron fine powder by oxygen-enriched air roasting of pyrite

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