Process method for co-preparing liquid hydrocyanic acid and sodium cyanide

Abstract

The invention discloses a process method for co-preparing liquid hydrocyanic acid and sodium cyanide. The process method is characterized by comprising the following step: performing an ammonia removal procedure and a deep cooling procedure on light oil cracking hydrocyanic acid mixed gas which is taken as a raw material, so as to obtain the liquid hydrocyanic acid, wherein the ammonia removal procedure comprises the specific steps of absorbing the hydrocyanic acid mixed gas by sulphuric acid aqueous solution; the deep cooling procedure is cooling the hydrocyanic acid mixed gas to minus 10 to minus 20 DEG C, after the hydrocyanic acid mixed gas is cooled, a part of the hydrocyanic acid gas becomes a liquid to obtain the liquid hydrocyanic acid, and the other part of the hydrocyanic acid gas is a tail gas containing hydrocyanic acid; the deeply-cooled tail gas containing hydrocyanic acid is absorbed by sodium hydroxide aqueous solution to prepare a sodium cyanide aqueous solution. According to the process method disclosed by the invention, by using a method of combining direct deep cooling under a micro-negative pressure with tail gas absorption, a purification efficiency for hydrocyanic acid and a utilization efficiency for hydrocyanic acid can be remarkably increased, meanwhile, energy consumption during a purification process for hydrocyanic acid is greatly reduced and can be reduced by 90% to the greatest extent; moreover, the utilization rate of hydrocyanic acid is greater than 99.9%.

Description

technical field [0001] The invention belongs to the field of chemical industry, and relates to a method for purifying hydrocyanic acid from a reaction mixture gas produced by cracking light oil and producing sodium cyanide by utilizing tail gas. Background technique [0002] Hydrocyanic acid is a widely used chemical raw material, which can be used in many fields such as medicine, pesticides, cosmetics, dyes, fertilizers, electroplating, polymer materials, photography, mining, metallurgy, etc. At present, the main production methods of hydrocyanic acid mainly include light oil cracking method, Andrussow method, BMA method and acrylonitrile by-product method. Light oil cracking is a production method in which light oil (or gasoline), liquid ammonia and caustic soda are used as the main raw materials, and petroleum coke particles and nitrogen are used as auxiliary raw materials. Mixing, preheating to 280°C, immersing the petroleum coke particle layer through the three-phase e...

AI Technical Summary

Problems solved by technology

This not only requires the water that absorbs prussic acid to be frozen to a lower temperature, which leads to high energy consumption for lowering the temperature, but also has a low concentration of prussic acid in the obtained prussic acid absorption solution (about 10 ~ 20g / L ), leading to low purification efficiency of hydrocyanic acid, and in order to distill the hydrocyanic acid dissolved in water, rectification and cooling are required to obtain high-purity liquid hydrocyanic acid. For every ton of hydrocyanic acid rectified, Consumption of steam up to 15 tons

In addition, it is impossible to completely absorb the hydrogen cyanide gas in the traditional hydrogen cyanide purification process. Therefore, a part of the hydrogen cyanide gas will be entrained in the absorbed tail gas, and the entrained hydrogen cyanide gas will be destroyed with the incineration of the tail gas. Lost, can not be fully utilized, therefore, the highest liquefaction rate of hydrocyanic acid is only 95%

[0004] Purification of hydrocyanic acid by the above methods has the disadvantages of complex purification process, high energy consumption, low utilization rate of hydrocyanic acid, and high cost, which are difficult to accept in industrial production