Environment-friendly nano calcium carbonate carbonation method

Abstract

The invention discloses an environment-friendly nano calcium carbonate carbonation method which comprises the following steps: S1, injecting lime slurry into a reaction kettle, stopping feeding when the feeding amount is 1/5-2/5 of the volume of the reaction kettle, and adjusting the rotating speed at the same time; introducing kiln gas into the reaction kettle, and discharging reaction tail gas after treatment; when the pH value of the slurry in the reaction kettle is 7.5-8.0, stopping air intake, and adjusting the rotating speed; and s2, injecting lime slurry into the reaction kettle containing the seed crystal, stopping feeding when the feeding amount reaches 4/5 of the volume of the reaction kettle, adjusting the rotating speed, stirring and aging; and introducing the kiln gas again, and when the pH value of the slurry in the reaction kettle is 7 and the slurry at the upper part and the lower part in the reaction kettle has no relative temperature difference, enabling the carbonation reaction to reach the end point. According to the method, the nano calcium carbonate with the average particle size of 40-100 nm is stably produced, and meanwhile, in the production process, the generated tail gas is treated and then discharged, so that the atmosphere is hardly influenced, and the environmental protection requirement is met.

Description

technical field [0001] The invention relates to the technical field of nano-calcium carbonate carbon preparation, in particular to an environment-friendly carbonation method of nano-calcium carbonate. Background technique [0002] Carbonation reaction is a common method for the chemical preparation of calcium carbonate. It uses limestone as raw material and calcines to obtain calcium oxide and kiln gas containing carbon dioxide. Calcium oxide and water are digested in a certain proportion to generate calcium hydroxide suspension, and then kiln gas is passed into the suspension to carbonize to form calcium carbonate cooked slurry. The slurry is surface modified, dehydrated, dried, and pulverized to obtain nano-calcium carbonate product. [0003] At present, in the domestic industrialized calcium carbonate production, the intermittent bubbling carbonization method is still the main method, and the reaction equipment is a bubbling reactor. This method generally has the problem...

AI Technical Summary

Problems solved by technology

Affected by the purity and excess of the reaction gas, a large amount of tail gas will be discharged from the exhaust port of the reactor; while the carbonation reaction is an exothermic reaction, strong water vapor will be generated during the reaction process, and many calcium carbonate particles will be entrained. Exhaust gas is directly discharged into the atmosphere, which will cause serious solid particle pollution

The calcium carbonate carbonization tower tail gas cooling recovery system announced by domestic patent CN208120764U realizes the separation and recovery of water vapor, carbon dioxide, and calcium carbonate particles in the carbonation tail gas by using an air-cooled heat exchanger; The carbonization tower tail gas dust removal device adopts a water-cooled dust collector with a spiral centrifugal cooling tube inside. In this scheme, the dusty tail gas passes through the water cooler and quickly cools down, and the water vapor, carbon dioxide, and calcium carbonate in the tail gas are removed by centrifugal force. Particles are separated, and the above two calcium carbonate tail gas solutions can both cool down the carbonation tail gas. However, because the patented equipment structure does not consider the carbonation reaction and adopts large-flow ventilation, most of the dust is due to the relatively large calcium carbonate particles. Due to the small wind speed and excessive wind speed in the pipeline, the exhaust gas containing water vapor will cool down and condense to form water droplets to absorb and settle dust. If this method is used for dust removal, the dust content of the exhaust exhaust gas will still be high

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