外文翻譯---波特蘭水泥的分法及生產(chǎn)

1、<p><b>　　外文資料譯文</b></p><p>　　Portland cement of its Types and Manufacture of Portland cement</p><p>　　Portland cement is made by heating a mixture of limestone and clay, or othe

2、r materials of similar bulk composition and sufficient reactivity, ultimately to a temperature of about 1450°C. Partial fusion occurs, and nodules of clinker are produced. The clinker is mixed with a few percent of

3、gypsum and finely ground to make the cement. The gypsum controls the rate of set and may be partly replaced by other forms of calcium sulfate. Some specifications allow the addition of other materials at the gr</p>

4、<p>　　Alite is the most important constituent of all normal Portland cement clinkers,of which it constitutes 50%--70%.It is tricalcium silicate (Ca3SiO5)modified in composition and crystal structure by incorporat

5、ion of foreign ions, especially Mg2+, Al3+ and Fe3+. It reacts relatively quickly with water, and in normal Portland cement is the most important of the constituent phases for strength development at ages up to 28 days,

6、it is by far the most important.</p><p>　　Belite constitutes 15%---30% of normal Portland cement clinker. It is declaim silicate (Ca2SiO4) modified by incorporation of foreign ions and normally present wholl

7、y or largely as theβ polymorph. it reacts slowly with water , thus contributing little to the strength during the first 28 days ,but substantially to the further increase in strength that occurs at later ages .By one yea

8、r, the strength obtainable form pure alit and pure belite are about the same under comparable conditions.</p><p>　　The aluminates phase constitutes 5%--10% of most normal Portland cement clinkers. it is Tri

9、calcium aluminates (Ca3Al2O6), substantially modified in composition and sometimes also in structure by incorporation of foreign ions , especially Si4+ , Fe3+, Na+ and K+. It reacts rapidly with water and can cause undes

10、irably rapid setting unless a set-controlling agent, usually gypsum, is added.</p><p>　　The ferrite phase makes up 5%-15% of normal Portland cement clinkers. It is tetra calcium aluminoferrite (Ca4AlFeO7) su

11、bstantially modified in composition by variation in Al/Fe ratio and incorporation of foreign ions. The rate at which it reacts with water appears to be somewhat variable, perhaps due to differences in composition or othe

12、r characteristics, but in general is high initially and intermediate between those of Alite and Belite at later ages.</p><p>　　The great majority of Portland cements made throughout the world are designed fo

13、r general constructional use. The specifications with which such cements must comply are similar, but not identical, in all countries and various names are used to define the material, such as OPC (Ordinary Portland Ceme

14、nt) in the UK, or Type I Portland Cement in the USA.</p><p>　　Specifications are, in general based partly on chemical composition or physical properties such as specific surface area, and partly on performan

15、ce tests, such as setting time or compressive strength developed under standard conditions. The content of MgO is usually limited to either 4 or 5%, because quantities of this component in excess of about 2% are liable t

16、o occur as periclase (magnesium oxide), which through slow reaction with water can cause destructive expansion of hardened concrete. Fr</p><p>　　Rapid-hardening Portland cement have been produced in various

17、ways , such as varying the composition to increase the alite content , finer grinding of the clinker , and improvements in the manufacturing process , e.g. finer grinding or better mixing of the raw materials . The alit

18、e contents of Portland cements have increases steadily over the one and a half centuries during which the latter have been produced, and many presentday cements that would be considered normal today would have been des&l

19、t;/p><p>　　Destructive expansion from reaction with sulfates can occur not only if the latter are present in excessive proportion in the cement, but also form attack on concrete by sulfate solutions. The reacti

20、on involves the Al2O3 containing phases in the hardened cement, and in sulfate-resisting Portland cements, its effects are reduced by decreasing the proportion of the aluminates phase, sometimes to zero. This is achieved

21、 by decreasing the ratio of Al2O3 to Fe2O3 in the materials. In the USA, sulfate-</p><p>　　White Portland cements are made by increasing the ratio of Al2O3 to Fe2O3, and thus represent the opposite extreme i

22、n composition to sulfate-resisting Portland cements. The normal, dark color .of Portland cement is due to the ferrite phase, formation of which in white cement must thus be avoided. It is impracticable to employ raw mate

23、rials that are completely free from Fe2O3 and other components, such as Mn2O3, that contribute to the color. The effects of these components are therefore usually </p><p>　　Portland cement is made from some

24、 of the earth's most abundant materials .about two-thirds of it is derived from calcium oxide, whose source is usually some form of lime-stone(calcium carbonate),marls, chalk, or shells(for example, oyster).the other

25、 ingredients-silica,SiO2,about20％;alumina ,Al2O3 ,about 5％; and iron oxide,Fe2O3,about 3％ are derived from sand shale, clays, coal ash, and iron ore metal slag. Because the individual ingredients must be fused and sinter

26、ed to produce new compounds the</p><p>　　The major trend in manufacture of Portland cement has shifted to a greater emphasis on the reduction of the energy consumed for its production and increasing use of c

27、oal to replace gas and oil, which were the major fuels for burning the clinker. Energy consumption is generally greater for the wet process; therefore most new plants use the dry process. The characteristics of the final

28、 product are not any different for either process. The world's largest kiln (as of 1957) produced about 7500 tons </p><p>　　Other types of kilns which have been used or are in the process of being develo

29、ped are vertical or shaft kilns, fluid-bed furnaces, and swirl calciners.</p><p>　　波特蘭水泥的分法及生產(chǎn)</p><p>　　波特蘭水泥是通過加熱石灰?guī)r和粘土的混合物，或者其他具有相似組成并具有活性的塊狀物來生產(chǎn)的，加熱的最高溫度可以達到大約1450攝氏度。當部分塊狀物融化時，熟料的結(jié)節(jié)就出現(xiàn)了。熟料和百

30、分之幾的石膏再混合，磨細就制成了水泥。石膏的添加量由率值決定，并且部分其他形式的硫酸鈣相化合物可以代替石膏。有些特種水泥允許在研磨階段加入一些材料。熟料一般由以下成分構(gòu)成：67％的氧化鈣，22％的二氧化鈣，5％的三氧化二鋁，3％的三氧化二鐵和3％的其他成分。熟料在正常情況下含有三個相：阿利特、貝利特、鋁酸三鈣及鐵鋁酸四鈣。其他幾個相如：堿金屬硫酸鹽、活性氧化鈣等，一般以微小量出現(xiàn)。</p><p>　　阿利特是普

31、通波特蘭水泥熟料中最重要的組成部分，其構(gòu)成占50％—70％。它與外來離子（尤其是Mg2+ , Al3+ 和Fe3+）結(jié)合在構(gòu)成上和晶體結(jié)構(gòu)上又發(fā)生了變化的硅酸三鈣。它與水反應特別快，是普通波特蘭水泥28天強度發(fā)展的最重要的組成相，這是迄今為止中重要的。</p><p>　　貝利特在普通波特蘭水泥熟料中占15％—30％。它與外來離子結(jié)合并且通常全部或大部分呈β晶形的硅酸二鈣。它與水反應很慢，因此，在開始的28天內(nèi)對

32、強度沒什么作用。但實際上，它會使以后齡期里的強度進一步增加。一年后，在合適的條件下，純的阿利特和純的貝利特獲得的強度大約相同。</p><p>　　大多數(shù)普通波特蘭水泥熟料中，鋁酸鹽相占5％—10％。它是在組成和結(jié)構(gòu)上被大幅度的改變，并切有時也和外來離子結(jié)合（特別是Si4+ , Fe3+, Na+ and K+）的鋁酸三鈣。它與水反應迅速，會引起不理想的凝結(jié)，除非加入控制凝聚劑，通常加入的是石膏。</p&g

33、t;<p>　　在普通波特蘭水泥熟料中，鐵素體相占5％—15％。它是在組成上大幅度改變Al/Fe比例和結(jié)合外來離子的鐵鋁酸四鈣。也許因為組成和其他特征的差異，氧化鐵與水反應的速度似乎有些變動，但總的來說，開始時速度很快，在以后的齡期內(nèi)處于阿利特預貝利特與水反應的兩種速度之間。</p><p>　　在整個世界上大多數(shù)波特蘭水泥的制造是為一般建筑設計的。在世界上所有的國家中，這種水泥的規(guī)格遵守類似，但不

34、完全相同。不同的名字被用來定義不同的材料，如英國的普通波特蘭水泥，或美國的I型波特蘭水泥。</p><p>　　一般來說，技術(shù)要求部分基于化學組成或物理特性（如比表面積），部分基于性能測試（如凝固時間或標準情況下產(chǎn)生的抗壓強度）。氧化鎂的含量通常被限制在4％—5％之間，因為大量的這部分氧化鎂超過2％時容易形成方鎂石，通過雨水的緩慢反應可能會使已硬化的混凝土發(fā)生膨脹性的破壞。游離氧化鈣便顯出相同的作用，并且它在一定

35、程度上限制了水泥熟料中阿利特含量的上限。三氧化硫的含量過高也能導致延遲膨脹，通常設置2.5％—4％含量的上限。堿金屬（氧化鉀和氧化鈉）可通過膨脹反應形成一定量的骨料，并且一些國家的規(guī)格限制它的含量，例如：0.6％相當量的鈉。其他上限組成被廣泛用于規(guī)范涉及物質(zhì)不溶于稀酸技術(shù)和灼燒損失。許多其他次要成分在對其生產(chǎn)過程中，其含量也被限制，或者性質(zhì)，或者兩者都有，并且在某些情況下，其規(guī)格是被限制的。</p><p>　　

36、快硬波特蘭水泥已經(jīng)用給各種方式生產(chǎn)出來，例如使阿利特含量增加來改變熟料組成，細末熟料并且對生產(chǎn)過程進行改進，如細磨或者加入更好的混合材料。波特蘭水泥中阿利特的含量在過去的一個半世紀期間一直在平穩(wěn)地增加，加入更好的混合材料也僅僅就在幾十年前就已經(jīng)出現(xiàn)了，和許多現(xiàn)代水泥一樣，將被視為正常的快速硬化。在美國水泥規(guī)格中，快硬波特蘭水泥被稱為早期強度高或III型水泥。</p><p>　　來自于硫酸鹽反應的破壞性擴張反應不

37、僅會出現(xiàn)過度比例的水泥，也會形成對混凝土侵蝕的硫酸鹽溶液。在水泥硬化階段所設計的氧化鋁相反應在耐硫酸鹽波特蘭水泥中，其影響可以降低通過減少鋁酸鹽的比例，有時其影響可降低至為零。這是通過減少三氧化二鋁與三氧化二鐵的比例來得到的。在美國，耐硫酸鹽波特蘭水泥被稱為V型水泥。</p><p>　　波特蘭白水泥是由增加三氧化二鋁對三氧化二鐵的比例來制成的，從而代表了由另一個極端組成的耐硫酸鹽波特蘭水泥。在通常情況下，顏色較

38、深的波特蘭水泥是由于含有鐵素體相的形成，因此在白色水泥中必須避免鐵素體相的形成。使用完全不含三氧化二鐵及其其他有助顏色成分的材料（例如二氧化錳），是不切實際的。在生產(chǎn)熟料過程中，這些成分的影響可以通過減少其還原性和快速淬火來減少到最低限度。除了阿利特，貝利特和硫酸鹽相，一些玻璃相可以形成。</p><p>　　波特蘭水泥與水的反應是放熱的，雖然在某些條件下，這可能是一個優(yōu)勢，因為它可以加速硬化，在其它條件下這是一

39、個劣勢，例如在建設大型水壩或修筑油井，在高溫或較大壓強下，水泥漿在長距離下被泵抽干。在粗磨過程中，可以得到緩慢演化的熱量，降低阿利特和鋁酸鹽相的比例可以降低這種熱演變。在美國的規(guī)格中包括定義一個II型水泥或中熱波特蘭水泥，和一個更極端的IV型水泥或低熱波特蘭水泥。II型水泥適用于一般的建筑水泥結(jié)構(gòu)并具有中等的抗硫酸鹽侵蝕性能。</p><p>　　波特蘭水泥由世界上最多的材料來生產(chǎn)的。大約有三分之二的原料是氧化鈣

40、，它以一些形式存在著，例如：石灰石（碳化鈣），泥灰?guī)r，粉筆，或貝殼（例如，牡蠣）。其他的成分——二氧化鈣，約含20％；三氧化二鋁，約含5％；三氧化二鐵，約含3％——取自砂頁巖、粘土、煤灰和鐵礦石金屬礦渣。由于各種組分必須融化燒結(jié)來形成新的化合物，這些組分必須磨碎通過200目的篩子以便于在合理的時間內(nèi)在窯中進行反應。此外，必須在以上氧化物的很有限的限度內(nèi)，進行原材料組合來制造有用的產(chǎn)品。其他元素的氧化物雖然說對睡你的燒成是必須的，但它們的

41、含量必須在一定的限度內(nèi)：這些元素包括氧化鎂；鉀鈉氧化物和磷氧化物（五氧化二磷）。把這些適當?shù)脑牧辖M合后，然后在球磨機，棒磨機或者輥磨機內(nèi)研磨。根據(jù)原材料的特性，干磨或是濕磨。磨完后把這些生料喂入窯系統(tǒng)，通常是一個回轉(zhuǎn)窯，在里面原料會被加熱到1482°C。這些原料在高溫作用下逐漸失去水分；隨后在954°C釋放出二氧化碳；在1260°C時，少量的液相開始出現(xiàn)。這些液相是高熔相形成的一個中介。最終的產(chǎn)品，被稱作

42、熟料，因為在整個燒成過程中，生料并沒有真的全部熔化，而是部分融化時再冷卻，然后在球磨</p><p>　　波特蘭水泥的制造主要趨于轉(zhuǎn)向更強調(diào)降低生產(chǎn)能耗，并越來越多的用煤來代替煤氣和油，煤氣和油過去是煅燒熟料的主要燃料。對于濕法生產(chǎn)來說，能源消耗過大；因此許多新的水泥廠使用干法生產(chǎn)。世界上最大的窯（1957年投產(chǎn)）每天可以生產(chǎn)7500噸熟料，平均每一天窯每天生產(chǎn)1800噸熟料。最新式的窯采用某種形式的預熱系統(tǒng)，這

43、一系統(tǒng)充分利用熱廢氣來給要進窯的原材料加熱；另外，在原料進入回轉(zhuǎn)窯之前通過使用輔助燃燒器來在原料上進行石灰石的脫碳。這些技術(shù)使得回轉(zhuǎn)窯變得短而且節(jié)省能源。因為這些技術(shù)的發(fā)展，世界上第一長窯（225米長，直徑7.5米）將仍會保持最長的窯。另外一個趨勢是走向一個新的窯研磨機，就是輥軋機。這種磨機可以利用余熱來干燥，本省又容易自動控制，而且其能源的消耗更少。這種研磨機一小時可以研磨出400噸的生料。一些員工在控制室除了采石場可以操作整個工廠。