Lin Gao Qiming

Chapter 339 Acids and Alkalis ([-])

Production safety was Ji Situi's biggest headache.Accidents in chemical plants are no different than 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 lax attitude of these former farmers towards dangerous goods really made him overwhelmed - he conducted several safety production educations and reprimanded a few guys who didn't wear protective clothing in accordance with the regulations

A few unlucky ones stood dejectedly and were scolded by him for half an hour.As far as the climate in Lingao is concerned, standing by the stove with full body protection is indeed torture.Fiberglass trouser covers, rubber aprons, long-arm gloves, and high boots are all airtight things, and even if you don’t work by the stove for a few minutes, you will be sweating profusely.

"Do you want to be like him?!" Ji Situi took out a medical atlas—he got it from a large book, and all the photos in it were photos of patients with chemical burns.

But the effect of the photo was so terrifying that it had the opposite effect.Several native workers came to beg him, saying they didn't want to do the job anymore.Ji Si Tui made a fuss about it.

After some appeasement, wishing, and hinting that if they quit, they would send the labor reform team to taste the frightening threat of the legendary Fu Youdi's whip, and finally calmed down the hearts of the people in the sulfuric acid workshop, and the production went back to normal.Only then did Ji Situi get out, and rushed to the caustic soda workshop.Outside the workshop, large and small water tanks have been piled up, and there is still a lot of salt.Bingfeng is leading people to install the equipment.

"Salt, tap water and water tanks are all there. Since the project is not over yet, let's prepare saturated salt water first." Bai Yu, who volunteered to bring students to help, said.Although he became a teacher, he was also a chemistry enthusiast.

"This salt is not good." Xu Yingjie shook his head, "Coarse salt! There are 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, and at the same time, it can also decompose chlorine and hydrogen.However, the salt sent by Yanchang Village is unrefined coarse salt, which contains not only sodium salt, but also various impurities such as potassium salt, magnesium salt, and sulfate. Impurities will affect the decomposition efficiency during production and damage precious electrodes.

Therefore, before electrolysis, coarse salt must first be treated and refined to remove impurities and make it into a pure saturated sodium chloride solution before it can be put into production.In modern time and space, there is an industrial system with a highly developed division of labor, and the caustic soda industry can completely purchase refined sodium chloride products.Here, everything has to be done by yourself.The more backward and primitive the industry is, the more self-supporting things will become.

Ji Sixui first analyzed the salt he sent. The salt in the salt field village is of high quality, and the content of sulfate, which has the greatest impact on electrolysis, is very small.This is good news for him: the industrial practice of removing sulfate is to use barium chloride-he doesn't have this thing, and barium chloride is a highly toxic chemical, even if it can be synthesized, he doesn't want to do it.As for the content of calcium salt and magnesium salt is not high, it is a very ideal industrial salt.

He asked people to pour baskets of coarse salt into the sedimentation tank, and after adding water to saturation, Bai Yu, who was in charge of refining the electrolyte, brought soda ash and caustic soda, and added them in proportion according to the composition of the brine obtained from the test. Make the calcium salt and magnesium salt therein chemically react with it to generate calcium chloride and magnesium hydroxide to precipitate out.The above clarified solution is the saturated sodium chloride solution used for electrolysis.Because of the addition of caustic soda and soda ash, a small amount of dilute hydrochloric acid is also used for neutralization.

The electrolysis of table salt in production is a continuous process, and saturated sodium chloride solution must be continuously replenished into the electrolytic cell.Therefore, the refining of brine is carried out continuously throughout the electrolysis process.

The batch-type refining method produced by one cylinder by one cylinder is simple in operation and simple in equipment, but the labor intensity is too large and consumes too much manpower.Generally, continuous refining is adopted in industry.Although Ji Situi did it in a native way, he still decided to automate the production as much as possible.

According to his own conditions—there is tap water supply—Ji Situi decided to use continuous operation in the desalination stage during the official production.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 by manpower to maintain a certain salt layer.The brine produced is saturated brine, which is introduced from the salt tank into the sedimentation tank for neutralization.

In order to reduce the labor intensity, the position of the brine tank is made into a ladder shape, one higher than the other, so that the brine can be transported by using the potential difference and the principle of siphon. .From low to high is the salt tank - sedimentation tank - neutralization tank.Finally, the saturated sodium chloride solution flowing out from the neutralization tank is sent into 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 still need to put caustic soda!" said Bai Yu, who led the students to deal with the brine.

Xu Yingjie said: "These are two different things. You are making refined brine, which is not the same as making caustic soda."

Bai Yu said: "Fortunately, we also brought a lot of chemical products. Otherwise, without them as an 'introduction', wouldn't it be impossible to start work?"

"It's not impossible." Ji Sixui said while paying attention to the reaction in the tank, "It's just a matter of hurting the electrode. It's not impossible to just physically refine sodium chloride. But it requires a lot of investment, and it has to be transformed directly. The salt industry equipment in Salt Field Village started.”

"The salt industry equipment in Yanchang Village has been changed a lot."

"Wang Gong's transformation project is mainly aimed at increasing production. He built a windmill to lift brine and drench it to shorten the time for brine concentration." Ji Situ has visited Yanchang Village several times because of his business relationship.

"When it comes to refining, there is absolutely no way without a boiler." Ji Sixui continued, "The planning committee originally said that we would build a refined salt factory in Bopu. Once our caustic soda workshop is put into operation, this project must be started. "

"The construction of the chemical industry is at its climax!" Xu Yingjie said with emotion.

"It's time for the chemical industry. Think about it: pesticides, chemical fertilizers, explosives, and medicines. Once these four magic weapons come out, they won't be able to dominate the world!" Bai Yu was enthusiastic.

"It's still a long way off. Don't try to become fat." Ji Situi said, "There are still many supporting facilities and equipment in the chemical industry. The actual problems in production must be solved gradually. For example, the first batch of sulfuric acid plant The sulfuric acid produced. The impurity content is very high, which is very dangerous in some chemical productions. But to improve the purity, many conditions must be met.”

He compared, "This is like a jigsaw puzzle. After making the three acids and two bases, we just found out the four corners of the jigsaw puzzle and saw hope, but it took a long time to really put together the complete pattern." time."

Xu Yingjie commented: "It's as if someone wants to use glycerin made by saponification to mix nitroglycerin. The theory is correct, but it will actually kill you."

The reaction precipitation process of the whole brine will continue for 24 hours.Ji Sixui took people to the lime kiln by himself.Quicklime is ready here.According to the data in the process manual, he calculated how much chlorine gas would be produced in the next 72 hours of continuous production, and how much slaked lime would be needed to absorb it.Weigh a sufficient amount of quicklime, and then slowly spray water on it to make it digest slowly.After the digestion is over, let the workers sift the slaked lime, then put it in a basket and transport it to the caustic soda workshop.

Ji Si backed down and asked Xu Yingjie to measure the moisture content of the slaked lime, which was about 3%. This ratio was a little too high, so he asked people to pile up the slaked lime in the shed for a few days. There was still some quicklime in the slaked lime to let the moisture Continue to digest the lime so that the moisture drops below the proper 1% after a few days.

After everything was ready, a large amount of white precipitate had been deposited in the brine refining tank the next day, and the clarified liquid above was extracted from the test results, which met the requirements of electrolysis.Bai Yu used the principle of a siphon to pump the clarified saturated sodium chloride solution to the heating tank, and Ji Situ set up firewood under the heating tank to heat the brine to 70°C.The heating is to remove the carbon dioxide in it.

The white precipitate in the sedimentation tank is collected, the main components of which are calcium chloride and magnesium hydroxide.Both are useful chemicals that cannot be easily thrown away.Especially calcium chloride, which can be used by pharmaceutical companies 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, as a refrigerant for refrigeration equipment, to deink waste paper... and finally it can be used to make tofu.

Ji Si Tui used the difference in solubility of the two in water to separate them-calcium chloride is easily soluble, while magnesium hydroxide is insoluble in water.Add water to dissolve calcium chloride and pour it out for further processing.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 neutralizer for acid-containing wastewater; it can be used as an oil additive for anti-corrosion and desulfurization; Fuel.It is also an excellent desulfurizer, which is exactly what is needed in the exhaust duct of Ji Siti's sulfuric acid workshop, and it can effectively purify the polluted gas in the acid production process.

The heated sodium chloride is easily pumped into the electrolyzer to fill it up.Ji Situi pulled the switch, and the whole electrolysis process started automatically.He wore a set of anti-electricity protective clothing and anti-electricity rubber-soled shoes, and used a test pen to measure the surroundings of the electrolytic tank and the floor of the workshop-there was no leakage of electricity.

Electrolyte began to flow out of the outlet.The color was clear and there was no oozing of a hideous black liquid.He waited silently for 5 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.

"The caustic soda solution came out, right?" Bai Yu asked.

(End of this chapter)