12EN_CN 鹽田飽和鹵水直接進(jìn)蒸發(fā)罐真空制鹽工藝

1、鹽田飽和鹵水直接進(jìn)蒸發(fā)罐真空制鹽工藝介紹靳志玲（中鹽制鹽工程技術(shù)研究院，天津 300450）內(nèi)容摘要：利用灘田飽和鹵水直接進(jìn)蒸發(fā)罐蒸發(fā)結(jié)晶制取氯化鈉，在制鹽過程中采取三次洗滌方法，除去鈣鎂離子，以獲得純度超過99.1%的氯化鈉和濃度較高的制鹽母液。關(guān)鍵詞：灘田飽和鹵水 真空 精制鹽1 簡介目前，國內(nèi)大部分井礦鹽企業(yè)采用以井礦鹽鹵為原料，北方部分生產(chǎn)企業(yè)采用原鹽化成飽和鹽水再精制真空鹽的生產(chǎn)方法。 隨著國內(nèi)“兩堿”的迅速發(fā)展和人民生活水平的提高，原鹽供需矛盾已越來越突出。特別是在海鹽區(qū)，以原鹽溶解成飽和鹵水再生產(chǎn)精制鹽，不僅增加了原鹽的消耗，而且降低了鹽田面積的使用效率，增加投資，生產(chǎn)成本高，不

2、同程度上影響了食用鹽生產(chǎn)企業(yè)的經(jīng)濟(jì)效益，造成許多食用鹽定點(diǎn)生產(chǎn)企業(yè)減產(chǎn)、虧損，直接影響了百姓的生活。而采用灘田飽和鹵水直接進(jìn)蒸發(fā)罐制鹽，即可以節(jié)約結(jié)晶面積，其母液還可以為生產(chǎn)氯化鉀、氯化鎂等鹽化工產(chǎn)品提供高質(zhì)量原料苦鹵，達(dá)到充分利用鹵水中的各種有效成分，實(shí)現(xiàn)零排放、無污染、循環(huán)經(jīng)濟(jì)的目的。2. 工藝流程簡述鹵水經(jīng)灘田日曬蒸發(fā)，至飽和后引入一個(gè)鹵水庫中儲(chǔ)存。鹵水庫的作用，一是儲(chǔ)存一定量的飽和鹵水，以備真空制鹽生產(chǎn)的需要；二是鹵水在此有一定的停留時(shí)間，可以使其中的一些雜質(zhì)顆粒沉淀下來，達(dá)到凈化鹵水的目的。凈化后的飽和鹵水從鹵水庫引出后，進(jìn)入蒸發(fā)制鹽車間的精鹵桶。采用預(yù)熱后的鹵水進(jìn)罐，順流轉(zhuǎn)料、末效

3、排鹽漿，集中排母液的方式進(jìn)行生產(chǎn)。I效蒸發(fā)罐鹽箱中的鹽排到II效下循環(huán)管中，II效鹽箱中的鹽排到III效下循環(huán)管中，III效鹽箱中的鹽排到IV效下循環(huán)管中，最后集中在IV效鹽箱；IV效排出鹽漿，同時(shí)由IV效分離罐排出母液。工藝流程簡圖見圖1。3. 工藝的優(yōu)缺點(diǎn)運(yùn)用該工藝已在中國北方建設(shè)了一個(gè)年產(chǎn)15萬噸的真空制鹽生產(chǎn)線，相比再制鹽生產(chǎn)工藝，其實(shí)施效果如下：本工藝采用飽和鹵水制鹽，不需要淡水化原鹽，淡水消耗低，可節(jié)約淡水資源，根據(jù)生產(chǎn)情況，1t鹽消耗淡水1.4-0.2m3，而再制鹽生產(chǎn)工藝需要淡水3.5-4.53.73 m3，噸鹽節(jié)約了2.1-4.3 m3淡水。2）節(jié)約日曬鹽場土地，減少原鹽消耗

4、，提高了鹽田利用率對(duì)再制鹽生產(chǎn)線來說，一般生產(chǎn)1t精制鹽需要消耗1.2t日曬原鹽，年產(chǎn)15萬t的精制鹽需要18萬t原鹽，需要結(jié)晶面積136.36公頃（按目前中國北方鹽場有效結(jié)晶單產(chǎn)1650t/公頃，有效面積占80），采用飽和鹵水直接進(jìn)蒸發(fā)罐工藝，不需要飽和鹵水進(jìn)結(jié)晶池繼續(xù)蒸發(fā)制鹽，只需要建設(shè)一個(gè)約2公頃的飽和鹵庫，因此，節(jié)約了土地面積134.36公頃，節(jié)省的結(jié)晶面積可用于增加日曬鹽產(chǎn)量8547t，按日曬鹽銷售價(jià)160元/t計(jì)算，日曬鹽增加產(chǎn)值136.8萬元。如果土地按3萬元/畝計(jì)算，節(jié)約土地價(jià)值為6000多萬元。3）采用三次洗滌方法洗滌鹽漿以去除鈣鎂離子，使氯化鈉含量超過99.4，精制鹽達(dá)到優(yōu)

5、級(jí)鹽質(zhì)量。蒸發(fā)結(jié)晶過程中鹽漿會(huì)夾帶大量的母液，母液中含有大量的鈣、鎂雜質(zhì)，因此，采用三次不同的洗滌方式洗滌鹽漿，提高精制鹽質(zhì)量。4）用飽和鹵水直接生產(chǎn)精制鹽母液損失小，提高了母液的利用率，實(shí)現(xiàn)鹽化聯(lián)產(chǎn)采用鹽田飽和鹵水直接生產(chǎn)優(yōu)級(jí)真空精制鹽工藝，每產(chǎn)1t精制鹽副產(chǎn)母液約1.7m3，以年產(chǎn)15萬t精制鹽計(jì)算，全年可產(chǎn)生25.5萬m3蒸發(fā)母液，且排出的苦鹵氯化鉀含量達(dá)到了2430g/l，濃度為2934°Be´，鈉鎂比值為1.40.6，排出的苦鹵中氯化鉀總含量為6589t，氯化鎂總量為36540t，硫酸鎂總量為18900t，氯化鈉總量為37600t，溴總量510t。而年產(chǎn)18萬t原

6、鹽，排出的苦鹵量一般只有18萬m3，經(jīng)過復(fù)曬、滲透損失、溝道輸送進(jìn)入化工廠后只有原來的45左右，也就是說還有8.1萬m3，這時(shí)氯化鉀總含量為2036t，氯化鎂總量為15280 t，硫酸鎂總量為7727.4 t，氯化鈉總量為11128 t，溴總量162t。因此，該工藝可為鹽化工生產(chǎn)提供更多的原料，提高了生產(chǎn)效率，降低了各種消耗，節(jié)約能源。該工藝排出的制鹽蒸發(fā)母液溫度在55.04以上，可通過管道直接進(jìn)入下步生產(chǎn)氯化鉀的工序，生產(chǎn)氯化鉀產(chǎn)品，節(jié)約氯化鉀生產(chǎn)過程中所需熱量，折標(biāo)煤1157噸/年5）由于灘田飽和鹵水較化鹽鹵水氯化鈉含量低，因此單位產(chǎn)品的蒸發(fā)水量較高，噸鹽產(chǎn)品電、蒸汽消耗量較大，能耗較高。

7、6）蒸發(fā)設(shè)備換熱面積較化鹽溶解工藝稍高，因此設(shè)備投資相對(duì)較高，但由于節(jié)省大量鹽田結(jié)晶面積，總體投資低。4. 與原鹽溶解再制鹽工藝技術(shù)經(jīng)濟(jì)指標(biāo)比較國內(nèi)海鹽區(qū)生產(chǎn)真空鹽的工藝主要有灘田飽和鹵水進(jìn)罐蒸發(fā)制鹽和原鹽溶解制成飽和鹵水蒸發(fā)制鹽兩種方法。原鹽溶解制成飽和鹵水蒸發(fā)制鹽工藝優(yōu)缺點(diǎn)有：（1）需建結(jié)晶池，工程總體投資較高；（2）單位產(chǎn)品蒸發(fā)水量小，設(shè)備投資稍低，（3）噸鹽消耗電、蒸汽量較??；（4）水消耗較大，噸鹽產(chǎn)品耗水2.4m3，（5）蒸發(fā)母液損失大。比較兩種制鹽方法技術(shù)經(jīng)濟(jì)指標(biāo)如表。表 主要經(jīng)濟(jì)技術(shù)指標(biāo)比較項(xiàng) 目再制鹽生產(chǎn)飽和鹵水直接進(jìn)罐生產(chǎn)投資：結(jié)晶池投資550萬元0蒸發(fā)設(shè)備投資9701080

8、單位產(chǎn)品投資335元/噸306元/噸消耗指標(biāo)：原煤0.23噸0.21噸原鹽1.25噸1.15噸0.00噸鹵水0.007.5m3白水3.5-4.5 m31.4-0.2 m3電50-70度50-70度兩種工藝在投資和單位產(chǎn)品生產(chǎn)成本中有較大的差別，飽和鹵水法單位產(chǎn)品總投資低于原鹽溶解法，單位產(chǎn)品成本低于原鹽溶解法30。5. 結(jié)論對(duì)于北方海鹽區(qū)生產(chǎn)精制鹽企業(yè)來說，利用灘田飽和鹵水直接進(jìn)蒸發(fā)罐制取精制鹽是一個(gè)較好的生產(chǎn)工藝，節(jié)約投資，節(jié)約土地，特別是將寶貴的原鹽溶解成飽和鹵水再進(jìn)行制鹽是對(duì)土地資源的浪費(fèi)，再有其生產(chǎn)成本低，企業(yè)有較高的利潤空間；排出的制鹽母液綜合利用生產(chǎn)鉀、溴、鎂等產(chǎn)品，使鹵水全部吃干

9、榨凈，沒有廢物排放，減少了環(huán)境污染，有利于可持續(xù)發(fā)展。New technology of producing refined salt by adding salt field saturated brine into evaporator directly Jin zhiling Ge Jinyang (Salt Research Institute China Natural Salt Industry Corporation, TianJin 300450)Abstract: After Making saline saturated brine flow in evaporating

10、pot, the sodium chloride is obtained by evaporative crystallization. Calcium and magnesium ions can be removed by washing salt three times in order to get the sodium chloride that the purity is over 99.1 percent and the mother liquor that have high concentration.Key words: saline saturated brine, va

11、cuum, refine salt 81 BRIEF INTRODUCTIONAt present, the materials of making vacuum salt are using the well and rock salt in most of the well and rock salt corporations and the saturated brine got by dissolving crude salt. Along with the rapid development of caustic alkali and sodium carbonate and the

12、 growth in the peoples living standard, the contradiction of crude salt in supply and require is more and more stood out.Particularly in the sea salt areas, producting refine salt with saturated brine that is got by dissolving crude salt can increase the consumption of raw salt , reduce the availabi

13、lity factor of salt field, add investment and production cost. This willinfluence the economic efficiency of edible salt manufacturing enterprises , make them reduce output and affect peoples live.However, using the method of making saline saturated brine flow in evaporating pot and then obtaining s

14、odium chloride by evaporative crystallization can saving crystal area. Furthermore, the mother liquor can be used as material to produce chemically products such as potassium chloride, magnesium chloride etc. in order to make use of all kinds of effective constituents in the brine and achieve the ob

15、jects of no discharge ,no pollution and circulating economy.2. INDICATION OF THE PROCESS FLOWAfter being solarized to saturation in beach field brine was inducted to brine tank and stored. On the one hand brine tank can store some saturated brine that is used to produce vacuum salt. On the other han

16、d ,brine have some residence time here so some impurities can be deposited in order to make the brine be purified. After being drawouted from brine tank the cleaned saturated brine was pumped to fine brine tank in the manufacture salt plant. And production can be gone on by using the methods of preh

17、eating brine , transferring stuff in parallel flow, discharging salt slurry in the last effect and exporting mother liquor concentratedly. The salt in the first effect tank is discharged to the circulation pipe of the second effect, The salt in the second effect tank is discharged to the circulation

18、 pipe of the third effect, The salt in the third effect tank is discharged to the circulation pipe of the fourth effect. At last the salt is collected in the fourth effect tank where the salt slurry and the mother liquor are discharged. Fig. 1 is the diagram of the process flow. Figure.1 Diagram of

19、the process flow3. RELATIVE MERITS OF THE PROCESSIn the north of China a production line has been built with this process, which can produce 1.5 million tons salt per year. Comparing with rework salt production process, the effect of this process is as follows:1）The saturated brine is used in this p

20、rocess take the place of dissolving crude salt with fresh water. Such can reduce the consumption of fresh water and save the resource. According to the produce conditions, producing 1 ton salt will consume 1.4-0.2 m3 fresh water. And that if use the reworking salt process 3.5-4.53 m3 fresh water wil

21、l be used. That is to say 2.1-4.3 m3 fresh water can be saved corresponding to 1 ton salt .2) Saving the solar salt field, reduce the consumption of crude salt, increase the availability of the salt field. For the reworking salt production line, as a general rule producing 1 ton refine salt will con

22、sume 1.2 tons solar salt. Producing 1.5 million ton refine salt needs 1.8 million tons crude salt and 136.36 hectare crystal area(According to the experience that one hectare can produce 1650 ton crystal and the effective area is 80 percent). Using the process that the saturated brine is pumped to e

23、vaporating tank directly the brine need not evaporate in crystal pond but for a saturated brine storeroom of about 2 hectare. Such can save surface area of 134.36 hectare and this area can be used to increase 8547 ton output of solar salt. Hence the productive value of solar salt will increase 136.8

24、 ten thousand yuan according to the market price of solar salt which is 160yuan/t. And land value of 60 million yuan can be saved if the land is 30,000 yuan per mou. 3）Adopting the method of washing salt three times in order to get rid of calcium and magnesium ions , make the purity of sodium chlori

25、de exceed 99.4% and make the refine salt reach first quality. In the process of evaporative crystallization much mother liquor will exist in salt slurry. The mother liquor contains a lot of impurity of calcium and magnesium. So salt slurry is washed in three different ways in order to improve the qu

26、ality of refine salt.4）Using the saturated brine to produce refine salt can reduce the consume of mother liquors, enhance its availability and realize the production of salt and chemicals together. The process that producing excellent vacuum salt with salina saturated brine directly can get 1.7 m3 m

27、other liquor in relation to 1t refine salt. On the base of 150,000 ton refine salt, we can get 255,000 m3 evaporation mother liquor. In bitter brine whose concentration is 29340Be´the content of potassium chloride is 2430g/l and the ratio of sodium and magnesium is 1.40.6. And 6589t potassium c

28、hloride, 36540t magnesium chloride,18900t magnesium sulfate,37600t sodium chloride and 510t bromine are contained in the bitter brine.The bitter brine is about 180,000 m3 in relation to 180,000t crude salt. After being solarized repeatedly and consuming for filter the brine is left 45% when it is pu

29、mped to chemical plant. That is to say there are 81,000 m3 brine. By now there are 2036t potassium chloride, 15280t magnesium chloride, 7727.4t magnesium sulfate, 11128t sodium chloride and 162t bromine. So the process can provide more material for salt and chemicals plants, heighten production effi

30、ciency, reduce all kinds of consumption and save energy. The temperature of the mother liquor got from this process is over 55.04. So it can be pumped to the potassium chloride process with pipe to produce potassium chloride. Such will save the heat quantity in the process of producing potassium chl

31、oride. And the heat quantity is equal to 11578t/y standard coal.5) Because the content of sodium chloride in the beach saturated brine is lower than the content in the brine that is got by dissolving salt, the evaporated water of unit produce is higher, the electricity and steam consumption are more

32、. That is to say the energy consumption is higher.6）The heat exchange area is a littler bigger than the process of dissolving salt, so the equipment investment is higher. But because of saving a lot of salina crystal area the total investment is lower.4. COMPARE THE ECONOMIC INDICATORS WITH THE PROC

33、ESS OF DISSOLVING CRUDE SALT AND THEN REMAKING SALT In China There are two main methods to producing vacuum salt in sea salt area. One is pumping the beach saturated brine into evaporating pot. The other is using the saturated brine got by dissolving crude salt. Comparing the second method with the

34、first method the relative merits of the second method is as follows:（1）need to build crystal pond and the total investment is higher.(2)The evaporated water of unit product is smaller and the equipment investment is lower.(3)The consuming of electricity and steam is lower.(4)The consuming of water i

35、s more and 2.4 m3 water will be consumed in relation to 1 ton salt.(5)The loss of mother liquor is bigger. The economic indicators of the two methods are as follows:Comparison of the main economic and technical normsItemThe process by dissolving saltThe process by the saturated brine being pumped into evap