[0046] The following examples are intended to further illustrate the present invention, rather than limit the present invention.
[0047] The invention discloses a continuous mercury removal system and a mercury removal method for a high acidity chemical waste liquid containing mercury. The continuous mercury removal system is as follows: figure 1 As shown, it includes a waste liquid storage tank 1, a stripping reaction tower 5, a continuous vulcanization reaction device 14 and an adsorption tank 17 that are connected in sequence for containing high acidity and high mercury-containing chemical waste liquid;
[0048] The stripping reaction tower 5 is communicated with the hydrogen generator 3 and the steam generator 6 respectively through corresponding pipelines, a hydrogen storage tank 31 is provided between the stripping reaction tower 5 and the hydrogen generator 3, and the stripping reaction tower 5 is connected to the hydrogen generator 3. A steam storage tank 61 is provided between the steam generators 6; the gas outlet of the stripping reaction tower 5 is communicated with the adsorption tower 7, and the liquid outlet is communicated with the continuous vulcanization reaction device 14 through the acid-resistant pump 8;
[0049] The continuous sulfide reaction device 14 is communicated with the hydrogen sulfide generator 9 through pipelines, and a hydrogen sulfide gas storage tank 11 is also provided between the continuous sulfide reaction device 14 and the hydrogen sulfide generator 9. On the continuous sulfide reaction device 14 There is also a hydrogen sulfide gas return pipe 13 for returning excess hydrogen sulfide to the hydrogen sulfide gas storage tank 11; the sludge outlet of the continuous sulfide reaction device 14 is communicated with the sludge receiving tank 16, and the liquid outlet is communicated with the adsorption tank 17,
[0050] The lower end of the adsorption tank 17 is provided with a liquid outlet pipe 20; the adsorption tank is also provided with a mercury removal liquid return pipe 18 for conveying the mercury removal liquid, which is connected with the hydrogen generator 3 and the hydrogen sulfide generator 9 respectively.
[0051] The continuous mercury removal method for mercury-containing waste liquid of high acidity chemical industry includes the following steps:
[0052] The first step is the hydrogenolysis stripping process; the waste liquid containing more than 30% acid in the chemical waste liquid storage tank with high acidity and high mercury content is transported to the stripping reaction tower through an acid-resistant pump, and H is input into the stripping reaction tower. 2 and steam, hydrogenolysis stripping the waste liquid to remove organic mercury and elemental mercury; the removed elemental mercury vapor enters the adsorption tower, and the gas is discharged from the gas outlet after adsorption and purification; the liquid after hydrogenolysis stripping enters Continuous vulcanization reaction device; wherein the amount of hydrogen used is 1.2 times the theoretical reaction amount of organic mercury, and the vapor pressure of water vapor is 101-143 KPa; in this step, the removal rate of organic mercury is greater than 95%, and the removal rate of elemental mercury is greater than 98%;
[0053] The second step is the continuous sulfidation and mercury removal process; hydrogen sulfide gas is transported to the continuous sulfidation reaction device, and undergoes a gas-liquid reaction with the material in the continuous sulfidation reaction device to produce mercury sulfide precipitation, which flows out from the bottom of the continuous sulfidation reaction device. Entering the sludge receiving tank, the unreacted hydrogen sulfide gas rises and returns to the hydrogen sulfide storage tank for recycling through the return pipe arranged on the upper part of the continuous mercury removal device; The mercury removal rate of sulfide is greater than 99%;
[0054] The third step is the cascade adsorption process; the effluent from the continuous vulcanization reaction device is transported to the cascade adsorption tank, where the adsorption reaction occurs, and the mercury concentration in the waste liquid is less than 0.03mg/L after adsorption treatment. In this step, the total mercury adsorption efficiency is greater than 99%.
[0055] Preferably: the waste liquid contains hydrochloric acid or sulfuric acid or a mixture of the two; the mass concentration of the acid is 30% to 42%;
[0056] Preferably: after the organic mercury and elemental mercury are removed by hydrogenolysis stripping, a hydrogen sulfide conduit is arranged on the upper part of the hydrogen sulfide generator, and the hydrogen sulfide conduit is connected with the hydrogen sulfide storage tank; the hydrogen sulfide storage tank is connected to the first in the continuous mercury removal device. The primary and secondary mercury removal units are connected to the gas inlet pipe of the ejector through the inlet pipe of the aeration pipe;
[0057] Preferably: in the second step, the S/Hg molar ratio is 10.50.
[0058] Preferably: the removal rate of organic mercury in the hydrogenolysis stripping process of the method is greater than 95%, the removal rate of elemental mercury is greater than 98%, the rate of mercury removal by sulfide in the continuous sulfidation process is greater than 99%, and the mercury adsorption efficiency in the cascade adsorption process is greater than 99%.
[0059] The reaction principle of the method of the present invention is as follows:
[0060] 1) The principle of hydrogenolysis stripping mercury removal:
[0061] HgX 2 +H 2 →Hg O +2HX;
[0062] In the formula: X is an alkyl group;
[0063] Hg(s)+water vapor →Hg(g);
[0064] Hg(g)+Se=HgSe (ammalgamation)
[0065] 2) The principle of mercury removal by sulfide:
[0066] Hydrogen sulfide+Hg 2+ =HgS↓+2H +;
[0067] 3) Adsorption mechanism:
[0068] FeS 2 +Hg 2+ =HgS+FeS;
[0069] HgCl 2 + H-S-SAMMS = Cl-Hg-S-SAMMS+H + +Cl -.
[0070] The present invention has the following advantages:
[0071] 1. The mercury removal system and method of this scheme adopts three combined technologies of hydrogenolysis stripping mercury removal, continuous sulfidation mercury removal, and cascade adsorption mercury removal to realize that the chemical waste liquid with high acidity and high mercury content contains elemental mercury and mercury sulfide respectively. The form of high-efficiency removal, the acid solution used in the reaction process is the treated acid solution, and no additional cost will be added. After the mercury sulfide is precipitated and collected, the mercury can be recovered, and the recycling of mercury resources is realized;
[0072]2. The present invention adopts the hydrogenolysis stripping technology, which can effectively solve the problems of converting organic mercury into inorganic valence mercury and removing elemental mercury, and provides a guarantee for the realization of the mercury-containing high-acidity acid liquid that reaches the standard removal;
[0073] 3. The present invention adopts the continuous sulfide mercury removal technology, which can effectively solve the technical problems that valence mercury is converted into mercury sulfide precipitation and mercury sulfide back-dissolution under high acidity conditions;
[0074] 4. The invention finally adopts the stepwise adsorption mercury removal technology, which can ensure that the high acidity acid solution can be deeply purified, and then realize that the acid solution does not contain mercury, which provides a guarantee for the comprehensive utilization of the acid solution;
[0075] In addition, the system of the present invention is convenient to connect and install, and the process setting is simple and reasonable, which effectively solves the problem of mercury removal in the prior art.
