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Chapter 127 Acids and Bases 3
Production safety is the latest chapter that is Ji Situi's biggest headache. Accidents in chemical plants are no different than those in ordinary enterprises: worker casualties are not counted, equipment will be damaged, and the dire consequences of chemical leakage are even more difficult to predict. The casual attitude of these former farmers towards dangerous goods was too much for him - he conducted several safety production educations and scolded a few guys who did not wear protective clothing as required.
A few unlucky ones stood dejectedly while he scolded them for a full half hour. Considering the climatic conditions of Lingao, standing next to the stove while fully protected is indeed a kind of torture. Fiberglass trousers, rubber aprons, long-arm gloves and high boots are all airtight items. Even if you don't work near the stove for a few minutes, you will be sweating profusely.
"Do you want to be like him?" Ji Sidui took out a medical atlas - he got it from a big book. The photos in it were all of patients with chemical burns.
But the effect of the photo was so horrific that it had the opposite effect. Several indigenous workers came to beg him and said they no longer wanted to do this work. This made Ji Situi very angry.
After some appeasement, making wishes, and threatening to send him to the labor camp to taste the legendary Fu Youdi's whip if he didn't work, the people in the sulfuric acid workshop were finally appeased, and production returned to normal. Only then did Ji Sidui pull away and rush to the caustic soda workshop. Outside the workshop, there are already piles of large and small water tanks, as well as a large amount of salt. Bingfeng is leading people to install equipment.
"We have salt, tap water and water tanks. Since the project is not finished yet, we will prepare saturated salt water first," said Bai Yu, who volunteered to bring students to help. Although he became a teacher, he was also a chemistry enthusiast.
"This salt is not good." Xu Yingjie shook his head, "Coarse salt has too many impurities."
The principle of electrolyzing salt to make caustic soda is very simple. It directly electrolyzes saturated salt water to decompose sodium hydroxide, which is the so-called caustic soda. It can also decompose chlorine and hydrogen. However, the salt sent from Yanchang Village is unrefined coarse salt. It contains not only sodium salt, but also various impurities such as potassium salt, magnesium salt, and sulfate. The impurities will affect the decomposition efficiency during production and will cause damage. Precious electrodes.
Therefore, before electrolysis, the coarse salt must be processed and refined to remove impurities and become a pure saturated solution of sodium chloride before it can be put into production. In modern time and space, there is an industrial system with highly developed division of labor. The caustic soda industry can completely purchase refined sodium chloride products. Here, you have to do everything yourself. The more backward and primitive the industry becomes, the more things it needs to support itself.
Ji Situi first analyzed the salt delivered. The salt in Yanchang Village was of high quality and contained very little sulfate, which has the greatest impact on electrolysis. This was good news for him: the industrial method for removing sulfate was barium chloride - something he didn't have, and barium chloride was a highly toxic chemical. Even if it could be synthesized, he didn't want to do it. As for the content of calcium salt and magnesium salt, it is very ideal for industrial use.
He asked people to pour baskets of coarse salt into the sedimentation tank, and after adding water until it was saturated, Bai Yujie, who was responsible for refining the electrolyte, brought in soda ash and caustic soda, and added them in proportion according to the tested brine composition. The calcium salt and magnesium salt in it react chemically with it to generate calcium chloride and magnesium hydroxide and precipitate out. The clear liquid above is the saturated sodium chloride solution used for electrolysis. Because caustic soda and soda ash have been added, a small amount of dilute hydrochloric acid must be used for neutralization.
Electrolysis of salt during production is a continuous process, and saturated sodium chloride solution must be continuously replenished into the electrolytic tank. Therefore, the refining of brine is carried out continuously during the entire electrolysis process.
The intermittent refining method using one cylinder per cylinder is simple to operate and has simple equipment, but it is too labor-intensive and consumes too much manpower. Generally, continuous refining is used in industry. Although Ji Sidui did it in a local way, he still decided to make production as automated as possible.
Based on his own conditions - having tap water supply - Ji Sidui decided to use continuous operation in the saltation stage during formal production. The water flows in from the bottom of the special salt tank, passes through the salt layer in the tank, and overflows from the upper outlet of the tank. Salt is added intermittently manually to maintain a certain salt layer. The brine produced is saturated brine, which is introduced from the salt tank to the sedimentation tank and then neutralized.
In order to reduce labor intensity, the position of the brine tank is made into a ladder shape, one higher than the other, so that the position difference and siphon principle can be used to transport brine. . From low to high are the salt tank - sedimentation tank - neutralization tank. Finally, the saturated sodium chloride solution flowing out of the neutralization tank is sent to the heating tank.
This system is simpler than those used in industry and does not require any mechanical assistance. A small amount of manpower is enough.
"To make caustic soda, we actually need to put caustic soda," said Bai Yu, who led students to handle salt water.
Xu Yingjie said: "These are two different things. You are making refined brine, which is completely different from the production of caustic soda."
Bai Yu said: "Fortunately, we also brought a lot of chemical products. Otherwise, without them as a guide, we wouldn't be able to start work."
"It's not that bad." Ji Si retreated and said while paying attention to the reaction in the tank, "It will only damage the electrodes. It is not impossible to just physically refine sodium chloride. But it requires a lot of investment, and it has to be directly transformed. Salt industry equipment in Salt Farm Village begins.”
"The salt industry equipment in Yanchang Village has been improved a lot."
"The renovation project carried out by Wang Gong was mainly aimed at increasing production. The windmill he built was used to lift the brine and dry it, shortening the concentration time of the brine." Ji Sidui visited the salt field village several times because of business relationships.
"When it comes to refining, it's impossible without a boiler." Ji Sixui continued, "The Planning Commission originally said that we would build a refined salt plant in Bopu. As soon as our caustic soda plant is put into operation, this project must be launched. "
"The construction of the chemical industry," Xu Yingjie said with emotion.
"It's the turn of the chemical industry. Think about it: pesticides, fertilizers, explosives, and medicine. Once these four treasures come out, they won't dominate the world," Bai Yu said with great interest.
"It's still a long way off, don't think about becoming fat in one bite." Ji Situi said, "There are still many supporting facilities and equipment needed in chemical industry. Practical problems in production must be solved slowly. Let's talk about the first batch of sulfuric acid plant. The sulfuric acid produced has high impurity content, which is very dangerous in some chemical production. But to improve the purity, many conditions must be met."
He compared it, "This is like a puzzle piece. After making three acids and two bases, we have just found the four corners of the puzzle and saw hope, but it will take a long time to actually piece together the complete pattern." time."
Xu Yingjie commented: "This is like someone trying to use glycerin made by the saponification method to mix nitroglycerin. The theory is correct, but in fact it will kill people."
The entire brine reaction and precipitation process lasts 24 hours. Ji Sixui took people to the lime kiln by himself. Quicklime is ready here. Based on the data in the process manual, he calculated how much chlorine would be produced in 72 hours of continuous production and how much slaked lime would be needed to absorb it. Weigh out a sufficient amount of quicklime and slowly spray water on it to allow it to digest slowly. After digestion, workers sift the slaked lime, then put it in baskets and transport it to the caustic soda workshop.
Ji Situi asked Xu Yingjie to measure the moisture content of slaked lime. It was about 3. This ratio was a little too high, so he asked people to pile the hydrated lime in a shed and store it for a few days. There was still some quicklime in the slaked lime to allow the moisture to continue. Digest the lime so that after a few days the moisture drops below the appropriate 1.
After everything was ready, a large amount of white sediment had been deposited in the brine refining tank the next day. The above clarified liquid was extracted and the test results showed that it met the requirements of electrolysis. Bai Yu used the siphon principle to pump the clarified saturated sodium chloride solution into the heating tank. Ji Sihui set up firewood under the heating tank to heat the brine to 70°C. Heating is done to remove carbon dioxide from it.
The white sediment in the sedimentation tank is collected, the main components of which are calcium chloride and magnesium hydroxide. Both are useful chemicals and cannot be thrown away lightly. Especially calcium chloride, pharmaceutical companies can use it to make calcium chloride injections and tablets to treat various diseases caused by low calcium. In industry, it can be used as a commonly used desiccant, antifreeze in the construction industry, refrigerant liquid for refrigeration equipment, deinking waste paper, and finally used to make tofu.
Ji Situi used their different solubility in water to separate them - calcium chloride is easily soluble, while magnesium hydroxide is insoluble in water. Add water to dissolve the calcium chloride and pour it out for separate disposal. The insoluble part is magnesium hydroxide. Although magnesium hydroxide is not so versatile, as an alkali salt, it can replace caustic soda and lime as a neutralizing agent for acidic wastewater; it can be used as an oil additive to play an anti-corrosion and desulfurizing role; it can be used in insulation materials and as a building barrier. fuel. It is also an excellent desulfurizer, which is needed in the exhaust duct of Ji Situi's sulfuric acid workshop, and can effectively purify polluted gases in the acid making process.
The heated sodium chloride is easily pumped into the electrolytic cell and filled. Ji Sidui pulled the switch, and the entire electrolysis process started automatically. He wore a set of anti-electricity labor protection clothing and anti-electricity rubber-soled shoes. He used an electricity test pen to measure the surroundings of the electrolytic tank and the floor of the workshop - there was no leakage of electricity.
The electrolyte begins to flow out of the outlet. The color is clear and there is no horrible black liquid coming out. He waited silently for five minutes to calculate whether the flow of electrolyte was normal. Finally, he measured the temperature and voltage in the tank - everything was normal. Whether the temperature and voltage are normal determines the electrolysis efficiency in the tank.
"Is the caustic soda solution that came out?" Bai Yu asked. ,.
