Method for resource utilization of fluidized bed combustion ash residues

Abstract

The invention discloses a method for resource utilization of fluidized bed combustion ash residues. The method comprises the following steps of: mixing the fluidized bed combustion ash residues with water to obtain mortar, and crushing the mortar until the particle size is 1 to 20 micrometers; introducing flue gas of a coal-fired boiler until the pH value of the solution is lower than 7, and filtering to remove water to obtain the ash residues; mixing the ash residues with density separation liquid, collecting and separating out dross which floats on the surface layer of the solution; feeding material liquid into a centrifuge for centrifugally separating centrifugal residues of which the density is greater than that of the separation liquid; and filtering centrifugate in a filter to obtain residues, mxing the residues with the dross to obtain a mixture, activating the mixture in the absence of oxygen at a temperature of 300 to 500 DEG C, cooling and then crushing the mixture, cleaning the crushed mixture by using hydrochloric acid and water, and drying the cleaned mixture to obtain an adsorbent product. By adopting the method, adverse effects caused by calcium sulfite, unburned carbon granules and free calcium oxide on the products such as cement, concrete and the like are eliminated, and the calcium sulfite, the unburned carbon granules and other porous materials are separated from the products and used as useful waste water purification adsorbents, so that the utilization value of the fluidized bed combustion ash residues is improved.

Description

technical field [0001] The invention relates to sulfur-fixing ash, in particular to a resource utilization technology related to the ash produced in the desulfurization process in a dry furnace. Background technique [0002] Sulfur-fixed ash is a solid waste produced after sulfur-containing coal and limestone (mainly calcium carbonate) are mixed in a certain proportion and burned in a circulating fluidized bed coal-fired boiler (CFB) at 850-900 °C to fix sulfur. The main minerals in sulfur-fixing ash include calcium sulfite, limestone, quartz stone, free calcium oxide, hematite and calcium sulfate. The main minerals in fly ash are mullite, quartz and hematite and other ferrosilicon components with hydration activity, and there are less calcium sulfate and calcium sulfite in fly ash. In addition, due to the low combustion temperature of the CFB boiler, there is more incompletely burned carbon in the sulfur-fixed ash. Therefore, unlike ordinary fly ash, sulfur-fixed ash has ...

AI Technical Summary

Problems solved by technology

However, the cost of chemical oxidants is high and it is difficult to realize industrial utilization

Chinese invention patent (ZL200910103640.4) uses sulfur-fixed ash, cement clinker, and cement as raw materials to manufacture cement cementitious material products, and solves the problem of product expansion caused by calcium sulfite and free calcium oxide through high-temperature, high-pressure steam for long-term maintenance. However, the high-pressure curing time needs more than 12 hours, the work efficiency is low, and the energy consumption is high

Chinese invention patent (ZL201010237033.X) uses lime, sulfur-fixing ash, and bauxite as raw materials to make clinker at a temperature of 1100-1450°C for 10-90 minutes, which can be used for belite, calcium sulfoaluminate, iron The production of special cement with phase as the main mineral, but calcium sulfite is unstable and may be re-decomposed into sulfur dioxide during the calcination process at such a high temperature, causing environmental pollution

Therefore, when the sulfur-fixed ash is used as a raw material for cement, concrete and fired bricks, in order to ensure product performance, it can only be mixed in a small proportion, resulting in most of the sulfur-fixed ash being stacked because it cannot be effectively utilized, which not only occupies a waste of land, wasting resources, and polluting the environment