Chapter 13 Section 1 Mining and Processing of Salt in Ancient China

Salt (NaCl) is an essential nutrient for the normal maintenance of human life and growth and development, and it is almost impossible to do without it every day.As far back as the primitive human period, people lived a life of fishing and hunting, eating meat and drinking blood, and naturally ingested salt from the flesh and blood of animals, so there was no need to search for this substance.But in the middle and late period of the Neolithic Age, with the rise of agriculture, food began to advance to grain-based, so it was necessary for human beings to look for new sources of salt in nature.

There are many kinds of occurrence states of table salt in nature.Every year, a large amount of rainwater dissolves the salt in the soil, merges into streams, flows into rivers, and finally flows into the sea; the seawater is exposed to the sun every day and evaporates in large quantities, so the salt content is continuously concentrated, and seawater has become the most abundant salt resource.It is estimated that there are more than 100 trillion tons of table salt stored in the ocean, which can be said to be inexhaustible and inexhaustible. This is sea salt.Some rivers in the hinterland of the continent flow into lakes that do not reach the sea. In these areas, there is often little rainfall and a large amount of evaporation, so the salt in the lake water is continuously concentrated, so this kind of lake becomes a salt lake. A large amount of table salt will condense, which is lake salt, or pool salt.Of course, some salt lakes were originally part of the ocean, but due to geological changes, they later became inland salt lakes.If the salt lake dries up for a long time, a large amount of table salt will accumulate; sometimes due to changes in the earth's crust, the salt will be buried in the ground again, which forms rock salt, also called cliff salt.In areas with rock salt, a lot of table salt is naturally dissolved in groundwater. Once a well is opened to draw water, brine can be obtained, and the salt can be obtained by boiling marinade. This is well salt.From these occurrence states, it is not difficult to find table salt in nature.It is estimated that from the middle and late stages of the Neolithic Age, these natural salts from different sources gradually entered human life.But no matter what kind of natural table salt, there are always many impurities, mainly magnesium, calcium, potassium chloride, sulfate and sodium sulfate.Magnesium salt has a bitter taste, and eating it will cause diarrhea and is easy to deliquescence. Therefore, the processing technology of table salt is to extract and purify table salt from various natural salt water (sea water, well salt water, salt lake water, etc.).The work of this processing technology also emerged with the mining of salt, and is constantly improving.

The pre-Qin ancient book "Shiben" said: "During the time of the Yellow Emperor, the princes had the Susha family, who began to boil milk with sea water and fry it into salt. Its colors were green, yellow, white, black, and purple." Recorded in "Shangshu Yugong" : "Qingzhou Jue tribute salt, Ji." It is said that Xia Yu has ordered Qingzhou to pay salt, which shows that the Bohai Sea coast and Mount Tai area in Shandong Province were already rich in sea salt at that time. "Zhou Li Tianguan Zhongzai Chapter" records: In the Zhou Dynasty, Tianguan Zhongzai's subordinates had a "salt man", whose duty was to "handle the government orders of salt, and to share (supply) salt for everything."At that time, "bitter salt" and "loose salt" were enshrined during sacrifices. Yeast salt is used in meals, that is, the "salt scum", which is said to be Rong salt, that is, rock salt produced in the inland of Northwest China; "shaped salt" and "loose salt" are used to receive guests, and "shaped salt" is said to be "Salt that looks like a tiger" should be recrystallized reprocessed salt.It can be seen that a variety of salt resources have been developed in the Zhou Dynasty, and preliminary appropriate processing has been carried out.During the Spring and Autumn Period, Guan Zhong, the prime minister of Qi State, began to set up tax officials for salt. It can be seen that the consumption of salt was already quite large at that time.Since then, successive dynasties have set official taxes on salt affairs, and salt tax has become a major revenue of the state treasury.

Among the salt lakes in the hinterland of China in ancient times, the salt lake near Yuncheng, Shanxi Province is the most famous. Because the lake is on the east side of the Yellow River, it was called Hedong Salt Lake in ancient times.In the Song Dynasty, this place belonged to Anyi of Jiezhou, so it was also called Yanchi of Jiezhou.The collection of table salt from this salt pond may have started in prehistoric times. In "Warring States Policy", there is already a text describing the exhaustion of driving a good horse and driving a salt cart to climb the Taihang Mountains. The salt trafficked is probably the salt in the pool near Yuncheng.There is a saying "Jingshan, looking south at the salt dealer's lake", the said salt lake refers to the salt pond in the east of the river.

The land of Bashu is the birthplace of my country's well salt, and its mining is concentrated in Sichuan and Yunnan. Zigong, Sichuan Province is known as the ancient salt capital of China, and it is the center of invention of my country's well salt mining technology.Mining well salt in Shu was probably founded in the Warring States period. According to the records of "Huayang Guozhi·Shu Zhi" written by Jin Changzhu: "After the Zhou Dynasty was destroyed, King Qin Xiaowen (as King Qin Zhaoxiang) took Li Bing (about 265 BC - BC 251) was guarded by Shu. Ice can know astronomy and geography,...and know water veins, pass through the salt wells of Guangdu (now Shuangliu County), and various lands, so Shu has the people to keep healthy." Li Bing was a native of my country's Warring States Period Famous water experts.It may be that he discovered the underground brine in the Chengdu Plain when he led the people of Bashu to dig mountains and move soil and build the Dujiangyan project. "Huayang Guozhi Shuzhi" also said: "Nan'an County (now Leshan City, Sichuan Province)... ruled the Yijiang River in the Qing Dynasty. The county irrigates a famous beach, and it is called salt irrigation, which was flattened by Li Bing." It clearly pointed out that Li Bing had leveled Salt flats formed by the outflow of underground brine.At that time, after the Qin Dynasty took control of Shu, a large number of immigrants brought various advanced handicraft technologies from other places, including the well-drilling technology of the Central Plains; in addition, the population of Shu was soaring, and there was an urgent need for more salt supply.Under such circumstances, Li Bing pioneered the drilling of well salt, which not only enriched the country and benefited the people, but also promoted the technology of rock drilling and drilling.His feat can be said to be no less than his contribution to water conservancy.

Tao Hongjing (452-536 A.D.), a medical scientist in the Liang Dynasty, had made a fairly comprehensive overview of various salts in his "Ben Cao Jing Ji Zhu".He said: "Among the five flavors, this is the only one that is indispensable. There are East China Sea, North Sea Salt and Hedong Salt Pond; Liang and Yi (Liangzhou and Yizhou are both in the Bashu area) have salt wells; Vietnam) has South Sea salt; Western Qiang has mountain salt (i.e. Rong salt)...but the colors are different, and the one from the east of the river is the winner." Shen Kuo, a scholar of the Northern Song Dynasty, described it in more detail in his famous book "Mengxi Bi Tan" (Volume 11) Describes the distribution of various salt supply areas at that time.

According to historical records and combined with modern social surveys on salt production, we try to further explain the evolution of the production process of highly technical sea salt, pool salt and well salt. The ancestors of our country boiled the sea to make salt. As mentioned above, it is believed that the legend arose in the era when Shennong taught the people to harvest.As for the initial processing process is like?There is a lack of records, and it is now untestable.In view of the fact that the salt content in seawater is not very high, there is an average of about 27 grams per kilogram of seawater, and the salt concentration must exceed 265 grams per kilogram of seawater (30°C) to crystallize; if the seawater is directly boiled to extract the salt, Fuel consumption would be high and efficiency would be rather low.It is estimated that the coastal residents of our country have processed seawater into brine (that is, properly concentrated sea salt water) very early on, and then fried the brine into salt, which may be similar to the actions of people in the later Song Dynasty, or it may be a prototype of it.

According to the records in "Tu Jing Materia Medica" written by Su Song, a scholar of the Northern Song Dynasty, the production method of sea salt at that time was two steps: pouring sand to make brine and boiling brine to make salt.But sun-dried salt has not yet appeared, and this process continued until the Ming Dynasty. As for making brine by showering sand, it is to use the beach sand to absorb the salt brought up by the tide, and then either manually scoop water to soak the brine, or use the tidal leaching to obtain a thicker brine.As for which method to use, it depends on the height of the seaside terrain.In areas with higher terrain, the tide cannot be submerged, so the sea sand that has absorbed salt and has been dried in sunny days is scraped, piled up, and spread flat on the grass to form "slips" one by one. It is two feet high and more than one foot square, and each slide forms a channel.Dig a deep pit on the side behind each slide, called a bittern well.So a "luji" (bailer, commonly known as "yellow head") was used to scoop seawater for irrigation, so that the seawater soaked the sea sand, dissolved the salt, and turned into brine, which flowed into the brine well through the channel.If the beach is low-lying, then you can "dig the soil on the seashore as a pit, cover it with bamboo and wood, cover it with fluffy grass, and accumulate sand (beach sand that has absorbed a lot of sea salt) on it. Every tide washes the sand (or artificially Scoop the sea water nearby and pour it into the pit), and pour the brine and salt into the pit." In addition, dig a brine well on the side of the sand drenching pit, bury a small pipe under the sand drenching pit, and communicate with the well, so that the brine will flow into the well (Figure 4-1) .Before decocting the brine obtained by the above methods, it is best to estimate the concentration of salt in it. If it is too thin, it will still consume a lot of fuel, which is uneconomical and should be soaked in sand again.For this reason, there was a primitive method in the Song Dynasty, which can be said to be the prototype of the modern "floating and sinking method"."Xixi Congyu" written by Yao Liang of the Song Dynasty said that eggs and peach kernels were used to test the proportion of brine in Fujian, and the brine that could make them float was regarded as the best concentrated brine."Taiping Huanyu Ji" written by Song Renle Shi mentioned that 10 stone lotuses (that is, old lotus seeds sunken in the mud at the bottom of the pond) with different specific gravity were used to "taste its thickness (brine concentration)".The ones that make 10 whole floats are high-quality brine; the half-floated ones can be barely boiled;This method has made great progress since the Yuan Dynasty.

During the Yuan and Ming dynasties, salt people discovered that the ash obtained from burning rice and wheat stalks has a strong adsorption effect on sea salt, far better than sea sand, so it was widely used soon. "Shu Garden Miscellaneous Notes" and "Tiangong Kaiwu" written by Song Yingxing in the late Ming Dynasty have quite detailed records.This brine making method is also divided into two types due to the different terrain of the seashore.The first type: "High weir land, where the lake waves do not soak, the land can be planted with salt (Figure 4-2). If there is no rain in Dujie Dynasty (morning of the next day), rice, wheat, grass ash and reed grass ash will be widely distributed today. Put it on the ground (on the seaside salt beach), and press it to make it even. In the morning when the fog is rushing, the salt grass will bloom under it. When the sun is clear in the middle of the day, the ash and salt will be swept up and fried." This refers to the high-yang terrain. The beach uses plant ash to absorb the salt in the sea sand.The "Salt Law Discussion" written by Wang Shouji of the Qing Dynasty also said: "In autumn, mow the grass and fry the salt and store the ashes. Brine." It can be seen that plant ash can be used repeatedly.The second is where the beach is low and the tide can often submerge. "Burnt the grass into ashes, spread it on the beach, and then soak it with sea water. After drying, it will turn white, and then sweep it and drench it again." (See "Shuyuan Miscellaneous Notes")

After obtaining a sufficiently thick brine, you can decoct the sea salt.The pot for frying sea brine was called "lao pot" in the Han Dynasty, and it was generally called "salt pan" after the Song Dynasty.According to the "Pictures of Materia Medica", there are two types of salt cooking utensils, one is "drum iron", which is cast with pig iron, which is of course more durable, but the cost is high; the other is woven with bamboo strips, The inside and outside are coated with a thick layer of quicklime burned from seaside oyster and other shells, so that it can withstand grilling. It is "wide, deep, and flat-bottomed", and its shape is like a plate. It can be seen that it is very large. Although it is easy to burn out, materials can be obtained locally and the cost is low.Figure 4-3 is a depiction of the scene of tormenting sea salt in the Song Dynasty in "Tu Jing Materia Medica".

It is also worth mentioning that "Taiping Huanyu Ji" has mentioned the method of "scattering saponins in a plate" adopted by salt households in Hailing (now Taizhou, Jiangsu) to flocculate the loose crystals of salt, so as to facilitate the precipitation and growth of salt crystals. .Chinese saponin is the seed of saponins, a leguminous plant, and its bean flour can produce a lot of foam when put into water, so it will absorb small grains of table salt and make them agglomerate.In the Ming Dynasty, all salt households adopted this method more generally. The records in "Tiangong Kaiwu" are very detailed: "When the stew is not fried, it will condense, crush the saponins, mix with corn and sugar, and boil with stew. Put it into it and stir it, and the salt will be formed in an instant, and the saponin will form salt, just like gypsum forms tofu." This can be regarded as an interesting invention in the frying salt process. In the process of boiling the brine, the brine gradually thickens, and finally salt grains will be precipitated.In order to obtain table salt, one is to completely dry the brine, and the other is to remove the precipitated salt crystals while cooking, add new brine, and then boil and fish again.Comparing the two methods, "Boiling Botu" says: The latter method "continues to produce salt day and night, which is more labor-saving than the same method of drying the salt one by one." That is to say, the continuous operation of the salt production method is more economical and efficient. high. The method of sun-drying sea salt appeared quite late in our country, and it only emerged in Fujian during the Yuan Dynasty.Around the middle of the Ming Dynasty, more areas had changed from frying to drying.But at that time, most sea salt drying methods were just replacing decoction with sun exposure, and had not yet got rid of the process of prefabricating brine (drenching brine). Around the time of Zhengde and Jiajing in the middle of Ming Dynasty, the Changlu Salt Field was built in Cangzhou, Hebei, and a complete sun-dried salt method basically similar to the modern sea-salt sun-dried method appeared.Since then, the salt field has developed rapidly and soon became the center and model of sea salt production in China. From the late Ming Dynasty to the early Republic of China, the specific steps for drying salt on the beach were as follows: Dig tidal trenches on the seashore in advance to wait for the seawater to flood in.On both sides of the ditch, sun-drying pools with seven or nine floors (the highest can reach 12 floors) are built.This kind of drying pool is called "halogen platform" in Changlu, Shandong and Liaoning, "Shage" in Huaibei, "Yancheng" or "Shichi" in Fujian and Guangdong.When the tide is high, the ditch is filled with seawater. After the tide ebbs, the seawater in the ditch is scooped or carted into the drying pool on the highest layer, filled with water for exposure, and after being properly concentrated, it is put into the drying pool on the next layer.So layer by layer to the lowest pool.In this process, the above-mentioned stone lotus seeds are generally used to estimate the brine concentration.When it has become a concentrated brine, it will be exposed to the sun while it is sunny, so a grain of salt will be obtained.However, in the early years of the Qing Dynasty, the Catholic priests passed on the experience of the so-called "salt drying method" created by the Sicilians in Italy (about a thousand years ago), which was appreciated by Emperor Kangxi. and rewards, so it was promoted in Liaodong and Changlu.Later, the salt fields along the coast gradually introduced and integrated this method.Since then, the method of drying sea salt has gradually completely replaced the method of "decocting sea brine". The salt ponds in my country are mainly distributed in the arid or semi-arid areas in the west and north, that is, from Xinjiang in the west to Qinghai, northern Tibet, Shaanxi, Gansu, Ningxia, Inner Mongolia, Shanxi, and Jilin and Heilongjiang in the east. .However, Jiechi in the ancient Anyi area of ​​Shanxi Province, which is now near Yuncheng, is the most famous. From the late primitive society to the early Han Dynasty, the production method of Yuncheng Salt Lake was probably just to organize a large number of manpower to harvest the table salt naturally crystallized from the brine, that is, the decomposed salt at that time was still natural rock salt. "Hanshu Geography" records: "The salt pond is in the southwest of Anyi. The water in this pond is seventy miles from east to west and seventeen miles from north to south. It is purple and clear, muddy but not flowing, and the water comes out of rock salt. Never detracts.” However, the brine in the solution pool is of the SO·Cl—Na·Mg type, that is, a mixed solution of NaCl, MgCl, NaSO, and MgSO. Because the solubility of NaCl is relatively small compared to other components, when the pool water evaporates, NaCl will often be dissolved first. crystallized out.However, with the continuous crystallization of NaCl and the long-term uninterrupted "intensive mining", the salt content in the brine will drop significantly, and naturally crystallized rock salt will inevitably become less and less.However, with the increase of the population in the Central Plains, the demand for salt is constantly increasing. This situation will inevitably prompt the salt people (called "tinghu" in ancient times) to try to open up plots and use brine to dry salt, so as to assist the "collection of labor, fishing and harvesting". " to get more salt.Such pavilions had already appeared in the Spring and Autumn Period at the latest. In the Tang Dynasty, the production of furrow salt had been vigorously promoted and flourished.At that time, Zhang Shoujie made a detailed account in his "Historical Records of Justice".He said: "The salt pond in the east of the river is planted in a border. It is like planting a border of leeks. When it rains in the pond, the saltiness is even, that is, in the furrow on the water in the pack pond, it is about a foot deep. Expose it every day, and it will be completed in five or six days. Salt is like an alum stone, and its size is like Shuanglu (chess piece). When it is at dusk, it is called border salt." This kind of artificial land reclamation builds borders, introducing pool water that has been properly diluted by rain into the borders, and then relying on the sun and wind to build the borders. The method of blowing, evaporating, concentrating, and sun-drying table salt can crystallize the table salt separately from the brine, so that the output of pond salt will increase sharply, and the quality will also be improved. "Tu Jing Materia Medica" also has a vivid description of this salt-making method, with exquisite illustrations (Figure 4-4).Using this method to produce pool salt, the salt bed has been sun-dried and scooped for several degrees, and the concentration of NaSO, MgSO, etc. in the brine left is increasing and will inevitably crystallize out.Years and years like this, finally the surface of the salt bed is covered with a thick layer of nitrate (that is, Glauber's salt NaSO·10HO or white sodium magnesia NaSO·MgSO·4HO).So in the Ming Dynasty, Li Shizhen's description of this salt was slightly different.It said: "Pond salt comes from Anyi in Hedong and Lingzhou in Xixia (Lingwu in Ningxia). Today, it is only grown in Xiezhou. The brine is sparsely ridged, surrounded by moats, and water from the pool is injected. It will turn red for a long time, and it will be red in summer and autumn. When the south wind blows strongly, it will form overnight, which is called the salt south wind." In the Song Dynasty, "take the cultivated land as a border" to "sparse brine land as a border", and "brine land" is the lakeside land that has been covered with nitrate plates. , a letter difference, reflecting the changes in the appearance of the salt field.Then "Tujing Materia Medica" all mentioned that salt flowers crystallize when "the south wind blows", what is the reason? "Hedong Salt Law Review" records: In case of "northeast and southwest winds, the salt flowers do not float, and the full border is like boiling porridge, which is called 'porridge hair'.It can be seen that the root cause of this situation is that the northeast wind or west wind is a cold wind, which will cause the temperature to drop sharply, causing a large number of fine crystals of kabeinite to precipitate and mix into the salt grains to form porridge, making the salt "bitter". The production fails; while the south wind is a hot wind, which can accelerate the evaporation of brine and "formation of table salt overnight", and slightly increase the solubility of Glauber's salt and magbeinite to inhibit their crystallization, thus increasing the The quality of pool salt. The land of Bashu is the center of well salt mining in my country.This table salt exploits underground natural brine and solid rock salt by drilling wells, so the main technical problem is drilling wells.From the early Qin Dynasty when Li Bing dug Guangdu salt wells to the early Zhao and Song Dynasties, it can be said that the first stage of the development of salt wells in my country can be called the period of large-mouth shallow wells. The technology is relatively primitive and only shallow brine can be exploited.It is mainly done by manpower, using simple excavation tools such as hoes, hoes, and chisels. At least one person must leave room for digging, soil transportation, etc. in the passageway, so the diameter of the salt well is very large.The typical large wells in history can be cited as the "Lingjing" dug in Renshou County, Central Sichuan Plain during the Tang Dynasty, which reached 30 feet in width and 80 feet in depth.Around the beginning of the 1950s, archaeologists found a portrait brick that clearly depicted a vivid panorama of well salt production (Fig.There is a large salt well on the left side of the picture. There is a pulley on the top of the derrick, and there are four salt workers facing each other on the top of the derrick. They draw brine up and down and pour it into the brine pond next to it.The brine is transported over the mountains and mountains to the salt stove on the right in the picture through the "jian" (jianjian, a brine pipeline connected by big bamboo).There is a brine storage tank in the kitchen room.The brine is poured from the brine tank into the salt pot.Salt workers went to the mountains to cut firewood and boil salt with firewood.This scene shows that the production of well salt in the Han Dynasty has been mechanized to a certain extent, and the production scale is quite large.Regarding boiled salt, the Bashu region had begun to use natural gas as fuel to boil well salt at the latest during the Three Kingdoms period. After the turmoil during the Five Dynasties period, and during the Northern Song Dynasty, the society became more stable and the economy returned to prosperity. The population of Bashu increased sharply, and the supply of salt was tight. The government relaxed its control over the salt industry and let the people open salt wells.Chuanmin boldly innovated, adopted small-diameter drilling technology, and invented the "Zhuotong well".Since then, my country's well salt technology has reached a new level and entered the second stage of development.This invention appeared around the Qingli period of the Northern Song Dynasty (AD 1041-1048).Zhuotong Well is a small-diameter salt well, and its excavation and brine mining techniques generally include three aspects: (1) Invented the percussive drilling and sinking method, using the drill bit - "Wang Dao" to dig the well; (2) Use giant bamboo to remove joints, connect end to end to form a casing and run it into the well to prevent the sand and stone from falling into the well wall and the surrounding fresh water from immersing; (3) Invented the brine-drawing tube, which is to install the cooked skin at the bottom of a section of bamboo tube to form a one-way valve. Whenever the bamboo tube is immersed in underground brine, the brine will stimulate the leather valve to open up, and the brine will enter the tube.Whenever the bamboo tube is lifted, the brine in the tube will press the leather valve to close and the brine will not leak. In short, Zhuo Tongjing’s invention created a precedent for percussive drilling in the West, and is known as the "father of oil drilling" in modern times. As for the method of boiling salt, at least as early as the Han Dynasty, it was adopted in the Bashu Well Salt Area. The method used is called "open pot boiling salt", which has been continued until now, but the details are constantly being improved.According to the records of "Sichuan Salt Law Records" and "Fushun County Chronicles", it can be seen that some measures of boiling salt in the late Qing Dynasty were very similar to the crafts of Zigong salt wells today, and contained a lot of technical experience with scientific significance.For example: A, before boiling salt, often carry out the collocation of yellow bittern and black bittern, adjust the concentration.The NaCl concentration of yellow brine is about 100-150 g/L, and often contains some toxic BaCl; the NaCl concentration of black brine is about 170-200 g/L, and contains more sulfates.The ratio of brine is generally 6:4 or 7:3 between yellow brine and black brine.During this process, BaCl can be transformed into BaSO and precipitated. B. When the decoction is close to saturation, add soymilk to the brine to agglomerate sulfate impurities such as calcium, magnesium, iron, etc., and use its adsorption to trap some sediment and suspended matter, this "dregs" All float and gather on the surface", scoop it out with a ladle, and then "add soybean juice two or three times" until "the dregs are clear and the water is clear". C, when the brine is concentrated and clarified, add "mother and child slag salt". "Mother and child slag salt" is a well-crystallized table salt grain fried in a different pot, which can promote the crystallization of concentrated brine. "Sichuan Salt Fazhi" has a good explanation: "For the so-called 'mother and mother dregs', don't boil [marinated] water, add soybean juice, extinguish the fire after clarification, and smother (xun search) with a low fire. After a long time, the water The salt is formed like snowflakes. When the salt in the other pot is boiled and clarified, pour this into it, and the salt will become granules." D, wash away the "alkali", improve the salt quality, and prevent deliquescence.The so-called "alkaline" is actually a magnesium salt (MgSO, MgCl, etc.).Salt workers salvage the salt grains from the brine with long net spoons made of bamboo, "put them in bamboo vessels" (called "miaoyuan"), and then rinse the salt grains with "flower water". "For flower water, don't use salt water to cook for a long time, the water will rise immediately after adding soybean juice", so flower water is actually clarified saturated salt water.Therefore, it can wash away the alkalinity without dissolving the salt.The refined salt obtained in this way is called "flower salt", "uniform grain and white color, similar to plum blossom and borneol."