Method for preparing stannous chloride by recycling diluted hydrochloric acid tail gas

Abstract

The invention discloses a method for preparing stannous chloride by recycling diluted hydrochloric acid tail gas, which comprises the steps of adding hydrochloric acid and tin into a concentrated hydrochloric acid reactor, heating, reacting to form stannous chloride liquid, and gradually concentrating; generating dilute hydrochloric acid tail gas mixed by HCl steam and water vapor through reaction, entering a heat exchanger, feeding cold dilute acid salt in a cold dilute hydrochloric acid storage tank into the heat exchanger at the same time so as to obtain hot dilute hydrochloric acid by heating cold dilute hydrochloric acid through the hot dilute hydrochloric acid tail gas, feeding into a hot dilute hydrochloric acid heat preservation storage tank to be stored for standby application, and condensing the diluted hydrochloric acid tail gas and returning to a cold diluted hydrochloric acid storage tank for later use; and pumping the hot diluted hydrochloric acid in the hot diluted hydrochloric acid heat preservation storage tank into a diluted hydrochloric acid reactor, adding tin into the diluted hydrochloric acid reactor for reaction to prepare a stannous chloride solution, pumping the stannous chloride solution into a concentrated hydrochloric acid reactor for concentration after the reaction is completed, and then discharging, cooling and crystallizing to obtain stannous chloride crystals. The method can directly recycle dilute hydrochloric acid tail gas to prepare stannous chloride, and is energy-saving, environment-friendly and efficient.

Description

technical field [0001] The invention belongs to the technical field of stannous chloride preparation, in particular to a method for preparing stannous chloride by recycling dilute hydrochloric acid tail gas. Background technique [0002] Stannous chloride (SnCl 2 2H 2 O) Mainly used in electroplating industry, dyestuff, bleaching, mordant dyeing, decolorizing agent and analytical reagent and other industries. At present, the concentrated hydrochloric acid method is generally used to prepare stannous chloride, which is to naturally react tin with high-concentration hydrochloric acid, concentrate until the specific gravity of the solution reaches a specified value, then filter, cool, crystallize, and separate solid-liquid to obtain crystals. This method is simple in operation and stable in quality, but the reaction between hydrochloric acid and tin lower than 20%wt is slow at normal temperature, and basically has no industrial reaction value. Therefore, the preparation of st...

AI Technical Summary

Problems solved by technology

Because dilute hydrochloric acid contains a certain amount of tin, it limits the use of dilute hydrochloric acid in other fields, and dilute hydrochloric acid is easy to form azeotropy and difficult to concentrate

At present, the treatment method of dilute hydrochloric acid is to use a large amount of alkaline substances to neutralize it to pH 6-9, and discharge it after clarification. There is a waste of resources such as dilute hydrochloric acid and alkaline substances, and the treatment cost is high, the amount of sewage is large, and there are many sediment residues. The treated water has high chlorine content, lead and cadmium occasionally exceed the standard, etc., and the pressure on environmental protection is high.

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