ammonium bicarbonate have metathesised to sodium bicarbonate (which…)and ammomium chloride. Filtration separates the solid bicarbonate from the remaining solution. The bicarbonate is passed to a rotary dryer where it loses water and carbon dioxide to give a fluffy crystalline mass known as light soda-ash which is mostly sodium carbonate. The fluffy mass is light because the riginal cystal shape is retained on the loss of carbon dioxide，leaving many voids.It is usually more convenient to make a more dense material and this is achieved by adding water(which cause recrystallization in a denser form)and further drying. 该工艺的基本路线如下,NH3 气于氨气吸收器中吸收于事先经纯化的海水中，纯化的海水以减小Ca+、Mg+离子的量。（Ca+、Mg+在生产过程中易产生沉淀而阻塞管道）。含NaCl 和NH4HCO3 的溶液经吸收了CO2 的吸收塔(CO2 气体量塔底向上流) 开始时形成(NH4)2CO3 然后再生成NH4HCO3。在工厂的下面步骤中,Nacl 和NH4HCO3 经复分解反应生成NaHCO3（以沉淀形式形成）和NH4Cl。过滤将固体NaHCO3 从溶液中分离。将NaHCO3 送至旋转干燥器，在该干燥器中, NaHCO3 失去水和CO2后生成疏松的晶体块（即轻质纯碱）它的主要成分为Na2CO3 蓬松的晶体块很轻, 是因为NaHCO3 失去CO2后, 留下很多空隙，而保留原来的晶体形状。通常要得到密度更大的物质很方便，加入水（水能引起咦密度较大的形式重结晶）进一步干燥即可实现。
It is debatable whether the actual chemistry given above is a good description of the process, but it certainiy aids understanding. For a detailed understanding, a great deal needs to be known about solubility products of multicomponent systems. The importan thing to know is that the system is complex and requires careful control at all parts of the process in order for it to operate effectively．
值得争议的是，上述的化学知识是否为该过程的很好的描述，但这些只是肯定有助于理解过程。想要对此过程有详细的理解，必须要熟悉该组分体系中关于溶度积的很多知识。需要知道的重要知识是，该体系是复杂体系，为了使该过程高效操作，需要对该过程每部分小心控制。
One disadvantage of the process is the amount of calcium chloride produced. Far more is produced than can be used，so much of the production is simply dumped (it …product). It would be advantageous to use all the input material in this process, for example producing hydrogen chloride from the chloride. 该过程的一个缺点是：产生的CaCl2 的量很大，其产生量比所需量大得多。因此，大部分CaCl2 只是简单的倒掉（CaCl2 毒性不大），如果能要该过程中的有的进料加以利用，那么该过程是有优势，例如，从该氯化物可产生HCl。
Uses of soda-ash．Of a11 soda-ash，50％is sold to the glassmaking industry as it is a primary raw material for glass manufacture. The fortunes of the industry are therefore strongly tied to glass demand. Soda-ash also competes directly with sodium hydroxide as an alkali in many chernical processes. Sodium silicates are another important class of chemicals deftved from soda—ash by reaction with silica at 1200～1400℃．Silica—gel is a fine sodium silicate with a large surface area and is used in catalysts，chromatography and as a partial phosphate replacement in detergents and soaps.
纯碱的用途，有50%的纯碱销往玻璃制造业,因为穿件是玻璃制造过程中的主要原料。因此纯碱工业的财富与玻璃需求量息息相关。纯碱作为一种碱在许多化学过程中与NaOH 存在直接竞争。Na2SO3 是由纯碱和SiO2 在1200-1400℃反应衍生而来的另一类化学物质。硅酸是具有大表面积细小颗粒的Na2SO3,可用于催化剂、色谱之中, 洗涤剂和肥皂中作为部分磷酸盐的替代品。
3. Electrolytic Processes for Chlorine /Caustic Soda
Introduction．Both chlorine and caustic soda have，at various times in the history of the chemical industry，been greatly in demand，but unfortunately for operators of electrochemical
plants, not always at the same time．Chlorine has been valued as a bleach．or a raw material for the production of bleaching powder，as a disinfectant in water supplies and as a raw material for plastics and solvents manufacture. Caustic soda has been used in the production of soda-ash, soap, textiles, and as a very important raw materialin an incredible variety of chemical processes． 简介，在化学工业法杖是的各个时期，Cl2 和NaOH 两者的需求量均很,但是不幸的是,对于电化学工厂的操作人员来说,两者的需求量必总是相同。Cl2 可作为漂白粉或作为漂白粉的生产原料, 水供应的消毒剂,以及作为塑料和溶解剂知道的原料。苛性钠用于生产纯碱、肥皂和纺织品, 以及在多种化学过程中作为一种十分重要的原料。
A1l the electrolytic processes have in common the electrolysis of salt to give chlorine and sodium hydroxide. The vast maj ority of production electrolyses a solution of salt, but there are some significant plants that electrolyze molten salt to give liquid sodium and chlorine．These are used by industries that need the liquid sodium，mainly in the production of tetra-alkyl lead petroleum additives, though the petroleum additive companies are diversifying and other uses may appear. There are essentially three different types of cell used for aqueous electrolysis：mercury cells, diaphragm cells and membrane cells．Membrane cells are really the only technology that is viable for new capacity in modem plants，but a large amount of old capaciW stin exists and many companies have not found it economical to replace even their mercury cells, despite the environmental implications.
所有的电解有着共同之处，盐的电解生成Cl2 和NaOH。大多数生产过程是电解（盐的）水溶液，但是有些重要的工厂，电解熔融盐生成Cl2 和液态钠。这些电解熔融盐的过程用用于重要液态Na 的工业。虽然石油添加剂厂家多种多样，设会出现液态钠的其他用途，但是他的主要是用于生产四烷基铅石油添加剂。质上用于水溶液电解过程有三种不同的电解槽：水银槽、隔板槽和膜电解槽。膜电解槽只是用于此案在化工厂中新的生产过程，但是还存在着大量的旧生产过程，尽管说阴曹涉及到对环境的影响，但是许多生厂家上位法此案膜片电解槽代替水印电解槽的经济性。
All electrolytic reactions are based on the idea of using electons as a reagent in chemical Reactions. The basic reactions of brine electrolysis can be written as follows:
所有的电解反应都是以电子作为化学反应的试剂的观点为基础。设水电解过程的基本反应可写成下式：
This reaction has a positive free energy(△G=421. 7 kJ／mol at 25~C)and needs to be driven uphill by electricity．该反应的自由能为正，因此，需要电驱使进行。
Like many basic chemical processes，though the reaction appears to be gloriously simple. There are some significant complications.For a start．the reaction products need to be kept, apart ; hydrogen and chlorine will react explosively if they are allowed to mix. Chlorine reacts with hydroxide to give hypochlorous acid (HOCI) and chloride (both wasting product and creating by-products). The hypochlorous acid and hypochlorite(ClO`)in turn react to give chloratc(ClO3`), protons and more chloride．Hydroxide reacts at the anode to form oxygen．which can contaminate the chlorine. All the reactions reduce efficiency and/or create difficult separation or contamination problems that need to be sorted out bcfore any products can be sold．The key to understanding the various types of process used for the electrolysis is the way they separate the reaction products．There are basically three types of electrolytic cell for brine electrolysis, though there are many variations of detail among the cells from difierent manufacturers．
像其他许多化学品工艺一样，尽管该反应看起来似乎极其简单，但是有一些方面很复杂。首先，该反应的产物必须分开，如果H2 和Cl2 允许混合在一起，它们会剧烈反应。H2 和Cl2
反应生成HOCl 和氯化物（两者均会浪费产物、生成副产物）。接着，HOCl 和次氯酸盐反应生成氯酸盐（ClO3-）、质子和更多的氯化物。OH— 在阳极区反应生成能污染Cl2 的O2。所有的这些反应可降低效率和（或）引起分解困难或污染问题。因此, 在产物销售之前, 有必要对这些反应清理。理解各种用于电解过程的关键是各种类型的过程分离反应产物的方式。尽管不同的制造商所用的电解槽在细节方面有着多种改变, 但是用于盐水的电解过程的电解槽基本可分为以上三类。
4．The Uses of Chlorine and Sodium Hydroxide
Sodium hydroxide has so many chemical uses that it is difficult to classify them conveniently．One of the largest uses is for paper—making，where the treatment of wood requires a strong alkali．In some countries this consumes 20％of production．Another 20％ is consumed in the manufacture of inorganic chemicals such as sodium hypochlorite(the bleach and disinfectant)．Various organic syntheses consume about another fifth of the production．The production of alumina and soap uses smaller amounts.
NaOH 的用途之多，以致很难将它们方便地进行分类。最大的用途之一是用于造纸，造纸业中木材的处理需要强碱。有些国家造纸业中NaOH 的消耗占其产量的20%，另外的20%用于无机化学品（如，次氯酸钠、漂白粉和消毒剂）的生产种有机合成约消耗另外的15%，氧化铝和肥皂的生产需要少量的NaOH。。
Chlorine is widely used in a variety of other products．About a quarter of all production world-wide goes into vinyl chloride，the monomer for making PVC．Between a quarter and a half goes into a vmiety of other products．Depending on the country，up to 10％goes into water purification. Up to 20%goes into the production of solvents (methylchloroform, trichloroethene, ect. ) though many 0f these are being phased out because of the Montreal Protocol. About 10%world-wide goes into the production of inorganic chlorine -containing compounds. A very significant use in some country for the bleaching of wood pulp，though this is another use coming under environmental pressure.
Cl2 广泛用于其它各种产品的生产。在全世界范围内大约有1/4 的Cl2 用于生产氯乙烯（生产PVC 的单体）。1/4 至1/2 的Cl2 用于水的纯化。尽管因为《关于消耗臭氧层物质的蒙特利议定书》多种溶剂正在被逐步淘汰，但是仍有高达20%的氯气用于溶剂的生产（如甲基氯仿、三氯乙烯等）。全世界范围内，大约10%的Cl2 用于无机含氯的化合物的生产。尽管Cl2 用于漂白木材浆是来自环境压力的另一种途径，但是在一些国家Cl2 的十分重要的用途是用于木材浆的漂白。
UNIT 7
Dinitrogen makes up more than three-quarters of the air we breathe，but it is not readily available for further chemical use．Biological transformation of nitrogen into useful chemicals is embarrassing for the chemical industry，since all the effort of all the industry‘s technologists has been unable to find an easy alternative to this．Leguminous plants can take nitrogen from the air and convert it into ammonia and ammonium—containing products at atmospheric pressure and ambient temperature；despite a hundred years of effort，the chemical industry still needs high temperatures and pressures of hundreds of atmospheres to do the same job．Indeed，until the invention of the Haber process，all nitrogen—containing chemicals came from mineral sources ultimately derived from biological activity．
虽然N2 占我们呼吸的空气3/4 以上，但是氯气不容易用于进一步化学应用。对化学工业来说，N2 的生成有用化学品的生物转化反应难以实现，因为所有的工业技术人员的努力（或尝试）还没有找到该过程的简单其他方法。在常压和室温条件下，豆类植物能从空气中吸入N2 将之转化为NH3 以及含NH4-的产物。尽管（化学工艺师）花了一百年的精力，要实现上述转化，化学工业仍然需要高温和上百个大气压的压力。直到Harber 过程的发明，所有的含N 化学品都来自于有生物活性的矿物资源。
Essentially all the nitrogen in manufactured chemicals comes from ammonia derived from the Haber-base process. So much ammonia is made(more…produced), and so energy-intensive is the process, that ammonia production alone was estimated to use 3% of the World‘s energy supply in the mid-1980s．
基本上，所生产的化学品中所有的N（元素）都来自于Harber 法得来的NH3。NH3 的生产之大，（尽管因为氨分子较轻，生产的其它产品的量更大，但其生产的NH3 的分子数要多于其他任何化合物），以及该过程的能源是如此的密集，以致于据估计，在二十世纪八十年代NH3 的生产就消耗全世界能源供应的3%。
1,The first Haber Process Ammonia Synthesis 1、Harber 法合成NH3
Introduction. All methods for making ammonia are basically fine-tuned versions of the process developed by Haber, Nernst and Bosch in Germany just before the First World War．N2+3H2~--'-'-\
引言. 所有的生产NH3 的方法基本都是以Harber 法为基础，稍稍加以改变，该过程是由Harber、Nerst、Bosh 在德国于一战前开发出来的。N2 +3H2≒2 NH3
In principle the reaction between hydrogen and nitrogen is easy; it is exothermic and the equilibrium lies to the right at low temperatures. Unfortunately, nature has bestowed dinitrogen with an inconveniently strong triple bond，enabling the molecule to thumb its nose at thermodynamics. In scientific terms the molecule is kinetically inert, and rather severe reaction conditions are necessary to get reactions to proceed at a respectable rate. A major source of ―fixed‖ (meaning, paradoxically ―usefully reactive‖) nitrogen in nature is lightning, where the intense heat is sufficient to create nitrogen oxides from nitrogen and oxygen·
原则上，H2 和N2 间的反应很容易进行，该反应是放热反应，低温时平衡向右移动。所不幸的是，自然界赋予的N2 一个很强的叁键，这使得N2 分子不易受热力学因素的影响。用科学术语来说，该分子是动力学惰性的。因此，要使该反应以一定的速度进行，需要相当苛刻的反应条件。实际上，―固定‖（意思相互矛盾，―有用的反应活性‖）氦的一种主要来源是闪电过程，闪电时生产大量的热量，把N2 和O2转化为N2O.
To get a respectable yield of ammonia in a chemical plant we need to use a catalyst.
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