Method for reducing concentration of sulfur trioxide in smelting roasting flue gas by using coking sulfur paste

Abstract

The present application belongs to metallurgical technical field, and relates to a method for reducing concentration of sulfur trioxide in smelting roasting flue gas by using coking sulfur paste, comprising the following steps: 1) sulfur paste slurrying; 2) smelting roasting; 3) acid making purification. The present application uses sulfur paste waste residue as a reducing agent of oxygen and sulfur trioxide in flue gas, so that the sulfur paste waste residue reacts with oxygen to consume oxygen in flue gas and generate sulfur dioxide gas; at the same time, the sulfur paste and sulfur trioxide in flue gas have a reduction reaction, and the sulfur paste and sulfur trioxide are both converted into sulfur dioxide; the generation of waste acid by the combination of sulfur trioxide and water in the acid washing and purification process is inhibited from the source, the acid concentration of waste acid is significantly reduced, the utilization rate of sulfur is improved, the corrosion of equipment is reduced, the cost of waste acid neutralization treatment is reduced, the coking plant sulfur paste waste residue is consumed, the normal operation of the whole process is ensured, and the environmental protection benefit and economic benefit are remarkable.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and in particular relates to a method for reducing the concentration of sulfur trioxide in smelting roasting flue gas using coking sulfur paste. Background Technology

[0002] Coking sulfur paste is a byproduct of the HPF desulfurization process in the gas desulfurization system of a coking plant. It contains a large amount of coal tar and ash residue, which is concentrated into sulfur paste waste with a certain water content. Because the coke oven gas contains a large amount of coal tar and ash residue, these substances enter the crude sulfur, resulting in crude sulfur with a low sulfur content and a grayish-black color. It cannot be used directly in industrial production and has low value. At the same time, because coking sulfur paste has a high elemental sulfur content, it is prone to oxidation reaction when heated during long-term storage, causing environmental pollution.

[0003] To reduce pollution and increase economic benefits, existing technologies use a sulfur melting kettle to purify sulfur from coking sulfur paste. However, this process has poor sulfur separation efficiency and releases large amounts of toxic gases during discharge, posing significant health risks. To ensure the emitted gases are non-toxic and harmless, Chinese patent CN105217578B discloses a process and apparatus for preparing sulfur from coking sulfur paste. This process requires further acid absorption, alkali absorption, and photolysis of the waste gas generated from heating the coking sulfur paste to obtain non-toxic and harmless emissions. Essentially, it is still a purification process for sulfur in coking sulfur paste, which is complex and costly.

[0004] Meanwhile, in the current domestic and international processes of oxidative roasting for complex gold concentrates, waste acid with a sulfuric acid content of 10-30 wt% is produced. This waste acid is mainly generated by the chemical reaction of sulfur trioxide in the flue gas with water during the acid washing and purification process. Furthermore, when sulfur trioxide encounters water vapor in the flue gas and the flue gas temperature is below the acid dew point, the two combine to form sulfuric acid vapor, which can cause severe corrosion to smelting equipment. Using lime neutralization to treat waste acid is costly, and the resulting waste gypsum is difficult to utilize comprehensively, impacting the economic benefits of enterprises. Therefore, reducing the concentration of sulfur trioxide in the gold smelting roasting flue gas to reduce the concentration of waste acid is of great significance.

[0005] Therefore, it is particularly important to research and develop a technical solution that can utilize existing resource advantages to simultaneously solve the comprehensive utilization of sulfur paste waste and reduce the concentration of waste acid generated during the roasting and smelting of gold concentrate, thereby improving the comprehensive utilization of hazardous waste. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention provides a method for reducing the concentration of sulfur trioxide in smelting roasting flue gas using coking sulfur paste.

[0007] The specific technical solution of the present invention is as follows:

[0008] A method for reducing the concentration of sulfur trioxide in smelting roasting flue gas using coking sulfur paste includes the following steps:

[0009] 1) Sulphur paste pulping: The cyanide lean liquor produced by the cyanide gold extraction process is used to adjust the coking sulfur paste to obtain pulped sulfur paste.

[0010] 2) Roasting and smelting: During the roasting and smelting process of sulfur-containing and arsenic-containing gold concentrate, the temperature of the flue gas when it comes out of the fluidized bed roasting furnace is controlled. When the flue gas enters the furnace gas cooler through the rising flue, the slurry-made sulfur paste enters the flue gas rising pipe in a mist form, so that the sulfur paste reacts with the flue gas.

[0011] 3) Acid production and purification: Spray washing is performed on the flue gas after the reaction to produce acid.

[0012] Furthermore, in step 1), the pulp concentration is controlled at 50-60%, and the pulping time is 2-8 hours.

[0013] Furthermore, in step 2), a high-pressure spray gun is used to spray the slurried sulfur paste into the flue gas rising pipe, and the pressure of the high-pressure spray gun is 1 to 3 MPa.

[0014] Furthermore, in step 2), the amount of sulfur paste added after pulping is 0.2 to 0.8 tons / hour.

[0015] This invention can monitor the oxygen content in the roasting flue gas in real time. When the oxygen content reaches a preset value of 0.4%, the sulfur paste waste residue is injected into the flue gas in a slurry-like mist. At the same time, the amount of sulfur paste added after slurrying can be adjusted according to the oxygen content. For every 0.1% increase in oxygen content, the amount of sulfur paste added increases by 0.15 to 0.25 tons / hour.

[0016] Furthermore, in step 2), the temperature of the flue gas exiting the fluidized bed roasting furnace during the roasting stage is controlled to be 500-700℃.

[0017] Furthermore, in step 3), the acid purification process adopts a wet purification process.

[0018] Furthermore, in step 3), the wet purification process involves the furnace gas from the electrostatic precipitator entering the empty tower and packed scrubbing tower of the purification section. The furnace gas is then sprayed and scrubbed, and adiabatically cooled to 50–70°C. Sulfur trioxide in the furnace gas is removed in this process, along with harmful impurities such as mineral dust, arsenic, and fluorine.

[0019] The volume ratio of oxygen in the flue gas treated by the method of the present invention is reduced to 0.2-0.4%, and the volume ratio of sulfur trioxide is reduced to 0.08-0.12%. After the flue gas undergoes an acid washing purification process, the concentration of waste acid produced is reduced from 10-30 wt% to 1-2 wt%.

[0020] Oxygen is a necessary condition for the oxidation of sulfur dioxide to sulfur trioxide. Therefore, removing oxygen from flue gas can inhibit the production of sulfur trioxide. This invention uses sulfur paste waste residue as a reducing agent for oxygen and sulfur trioxide in flue gas. The sulfur paste waste residue is injected into the flue gas in a slurry-like mist form. It consumes the oxygen in the flue gas by reacting with oxygen, generating sulfur dioxide gas. Since the oxidation reaction between sulfur dioxide and sulfur trioxide is a reversible reaction, when the oxygen concentration decreases, the reaction to generate sulfur trioxide proceeds in reverse. At the same time, sulfur paste reacts with sulfur trioxide in the flue gas, and both sulfur paste and sulfur trioxide are converted into sulfur dioxide. All of the above effects can increase the concentration of sulfur dioxide in the flue gas, inhibiting the combination of sulfur trioxide and water to form waste acid during the acid washing and purification process from the source, and significantly reducing the acid concentration of waste acid.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention inhibits the formation of waste acid from the combination of sulfur trioxide and water during the pickling and purification process at the source, significantly reducing the acid concentration of waste acid, improving the utilization rate of sulfur, reducing equipment corrosion, reducing the cost of waste acid neutralization treatment, consuming sulfur paste waste residue from coking plants, and ensuring the normal operation of the entire process, resulting in significant environmental and economic benefits. Detailed Implementation

[0023] The principles and features of the present invention are described below with reference to embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0024] Example 1:

[0025] The coking sulfur paste used in Example 1, i.e. sulfur paste waste residue, contains 10wt% water, 50wt% sulfur, pH=8, and 5wt% carbon.

[0026] A method for reducing the concentration of sulfur trioxide in smelting roasting flue gas using coking sulfur paste includes the following steps:

[0027] 1) Sulphur paste pulping: The cyanide lean liquor produced by the cyanide gold extraction process is used to adjust the coking sulfur paste. The pulping concentration is controlled at 50 wt%, and the pulping time is 2 hours to obtain pulped sulfur paste.

[0028] 2) Roasting and smelting: During the roasting and smelting process of sulfur- and arsenic-containing gold concentrate, the temperature of the flue gas exiting the fluidized bed roasting furnace is controlled at 500℃. When the flue gas enters the furnace gas cooler through the rising flue, the slurry-processed sulfur paste is sprayed into the rising flue gas pipe in a mist form using a high-pressure spray gun with a pressure of 1MPa, so that the sulfur paste reacts with the flue gas. By detecting that the oxygen content is 0.4%, the amount of slurry-processed sulfur paste added is 0.2 tons / hour, and the volume ratio of oxygen in the treated flue gas is reduced to 0.2%, and the volume ratio of sulfur trioxide is reduced to 0.08%.

[0029] 3) Acid production and purification: The flue gas after the reaction is purified by a wet process of spray washing to produce acid. The flue gas from the electrostatic precipitator enters the empty tower and packed scrubbing tower of the purification section. The flue gas is spray washed and adiabatically cooled to 50°C. Sulfur trioxide in the flue gas is also removed in this process. The concentration of the waste acid produced is reduced from 10wt% to 2wt%, and harmful impurities such as mineral dust, arsenic, and fluorine are removed.

[0030] Example 2:

[0031] The coking sulfur paste used in Example 2, i.e. sulfur paste waste residue, contains 15wt% water, 75wt% sulfur, pH=9, and 7.5wt% carbon.

[0032] A method for reducing the concentration of sulfur trioxide in smelting roasting flue gas using coking sulfur paste includes the following steps:

[0033] 1) Sulphur paste slurrying: The cyanide lean liquor produced by the cyanide gold extraction process is used to slurry the coking sulfur paste. The slurry concentration is controlled at 55wt%, and the slurrying time is 5 hours to obtain slurryed sulfur paste.

[0034] 2) Roasting and smelting: During the roasting and smelting process of sulfur- and arsenic-containing gold concentrate, the temperature of the flue gas exiting the fluidized bed roasting furnace is controlled at 600℃. When the flue gas enters the furnace gas cooler through the rising flue, the slurry-processed sulfur paste is sprayed into the flue gas rising pipe in a mist using a high-pressure spray gun with a pressure of 2MPa, so that the sulfur paste reacts with the flue gas. By detecting that the oxygen content is 0.6%, the amount of slurry-processed sulfur paste added is 0.5 tons / hour, and the volume ratio of oxygen in the treated flue gas is reduced to 0.3%, and the volume ratio of sulfur trioxide is reduced to 0.10%.

[0035] 3) Acid production and purification: The flue gas after the reaction is purified by a wet process of spray washing to produce acid. The flue gas from the electrostatic precipitator enters the empty tower and packed scrubbing tower of the purification section. The flue gas is spray washed and adiabatically cooled to 60°C. Sulfur trioxide in the flue gas is also removed in this process. The concentration of the waste acid produced is reduced from 20wt% to 1.5wt%, and harmful impurities such as mineral dust, arsenic, and fluorine are removed.

[0036] Example 3:

[0037] The coking sulfur paste used in Example 1, i.e. sulfur paste waste residue, contains 20wt% moisture, 90wt% sulfur, pH=10, and 10wt% carbon.

[0038] A method for reducing the concentration of sulfur trioxide in smelting roasting flue gas using coking sulfur paste includes the following steps:

[0039] 1) Sulphur paste pulping: The cyanide lean liquor produced by the cyanide gold extraction process is used to adjust the coking sulfur paste. The pulping concentration is controlled at 60wt%, and the pulping time is 8 hours to obtain pulped sulfur paste.

[0040] 2) Roasting and smelting: During the roasting and smelting process of sulfur- and arsenic-containing gold concentrate, the temperature of the flue gas exiting the fluidized bed roasting furnace is controlled at 700℃. When the flue gas enters the furnace gas cooler through the rising flue, the slurry-processed sulfur paste is sprayed into the flue gas rising pipe in a mist using a high-pressure spray gun with a pressure of 3MPa, so that the sulfur paste reacts with the flue gas. By detecting that the oxygen content is 0.7%, the amount of slurry-processed sulfur paste added is 0.8 tons / hour, and the volume ratio of oxygen in the treated flue gas is reduced to 0.4%, and the volume ratio of sulfur trioxide is reduced to 0.12%.

[0041] 3) Acid production and purification: The flue gas after the reaction is purified by a wet process of spray washing to produce acid. The flue gas from the electrostatic precipitator enters the empty tower and packed scrubbing tower of the purification section. The flue gas is spray washed and adiabatically cooled to 70°C. Sulfur trioxide in the flue gas is also removed in this process. The concentration of the waste acid produced is reduced from 30wt% to 2wt%, and harmful impurities such as mineral dust, arsenic, and fluorine are removed.

[0042] Therefore, it can be seen that the present invention is used and has significant effects.

[0043] In summary, this invention uses sulfur paste waste as a reducing agent for oxygen and sulfur trioxide in flue gas. The sulfur paste waste reacts with oxygen to consume the oxygen in the flue gas, generating sulfur dioxide. Simultaneously, the sulfur paste undergoes a reduction reaction with sulfur trioxide in the flue gas, converting both sulfur paste and sulfur trioxide into sulfur dioxide. The oxygen volume ratio in the flue gas treated by this method is reduced to 0.2–0.4%, and the sulfur trioxide volume ratio is reduced to 0.08–0.12%. After the acid washing purification process, the concentration of waste acid produced is reduced from 10–30 wt% to 1–2 wt%. This method inhibits the combination of sulfur trioxide and water to form waste acid during the acid washing purification process, significantly reducing the acid concentration of waste acid, improving sulfur utilization, reducing equipment corrosion, reducing the cost of waste acid neutralization treatment, consuming sulfur paste waste from coking plants, and ensuring the normal operation of the entire process. The environmental and economic benefits are significant.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reducing the concentration of sulfur trioxide in smelting roast flue gas by means of caking sulfur, characterized in that, Comprising the following steps: 1) Sulfur paste slurrying: The cyanide lean liquid produced by cyanide gold extraction process is used to pulp the coking sulfur paste, and the pulp concentration is controlled at 50-60wt%, and the pulp time is 2-8 hours; 2) Roasting smelting: In the roasting smelting process of sulfur-containing and arsenic-containing gold concentrate, the temperature of the flue gas from the boiling roasting furnace is controlled at 500-700℃, and when the flue gas enters the furnace gas cooler through the rising flue, a high-pressure spray gun is used to spray the slurry sulfur paste into the flue gas rising pipe in a misty manner, so that the sulfur paste reacts with the flue gas, the pressure of the high-pressure spray gun is 1-3MPa, and the addition amount of the slurry sulfur paste is 0.2-0.8 tons / hour; The oxygen content in the roasting flue gas is monitored in real time, and when the oxygen content reaches the preset value of 0.4%, the sulfur paste waste residue is sprayed into the flue gas in a slurry misty manner, and the addition amount of the slurry sulfur paste is adjusted according to the oxygen content, and the oxygen content increases by 0.1% every time, and the sulfur paste addition amount increases by 0.15-0.25 tons / hour; 3) Acid purification: The reacted flue gas is sprayed and washed to produce acid by using a wet purification process, the furnace gas from the electric dust collector enters the empty tower and the packed washing tower of the purification section, and the furnace gas is sprayed and washed, and the furnace gas is adiabatically cooled to 50-70℃.