外文翻譯---波特蘭水泥的分法及生產-預覽頁
【正文】 ally minimized by producing the clinker under slightly reducing conditions and by rapid quenching. In addition to alite, belite and aluminates phase, some glass may be formed.Portland cement is made from some of the earth39。 potassium oxide, K2O。F, a small amount at liquid phase forms. This liquid is the medium through which the highermelting phases are formed. The resultant product, called clinker because the whole never truly melts, is cooled and again ground, in ball mills to such a fineness that about 90％ will pass a screen having 325 openings per linear inch. The final product has a texture much like face powder. During grinding, about 5％ of calcium sulfate(gypsum or anhydride) is added to control setting time, strength development, and other properties.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 coal to replace gas and oil, which were the major fuels for burning the clinker. Energy consumption is generally greater for the wet process。s longest kiln (760 ft or 228 m long, 25 ft or m in diameter) will probably remain the longest. Another trend is toward a newer type of grinding mill, called a roller mill. This mill can use waste heat for drying, lends itself readily to automatic control, and uses less energy. These mills can grind up to 400 tons (360 metric tons) per hour. Several employees in a control room can operate a whole plant except for the quarry. Control is exercised by means of television monitors, sensors, puters, and automatic continuous chemical analysis.Other types of kilns which have been used or are in the process of being developed are vertical or shaft kilns, fluidbed furnaces, and swirl calciners. 波特蘭水泥的分法及生產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的，加熱的最高溫度可以達到大約1450攝氏度。有些特種水泥允許在研磨階段加入一些材料。阿利特是普通波特蘭水泥熟料中最重要的組成部分，其構成占50％—70％。它與外來離子結合并且通常全部或大部分呈β晶形的硅酸二鈣。大多數(shù)普通波特蘭水泥熟料中，鋁酸鹽相占5％—10％。它是在組成上大幅度改變Al/Fe比例和結合外來離子的鐵鋁酸四鈣。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。三氧化硫的含量過高也能導致延遲膨脹，％—4％含量的上限?？煊膊ㄌ靥m水泥已經用給各種方式生產出來，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過程進行改進，如細磨或者加入更好的混合材料。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。在通常情況下，顏色較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。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。波特蘭水泥由世界上最多的材料來生產的。此外，必須在以上氧化物的很有限的限度內，進行原材料組合來制造有用的產品。磨完后把這些生料喂入窯系統(tǒng)，通常是一個回轉窯，在里面原料會被加熱到1482176。C時，少量的液相開始出現(xiàn)。波特蘭水泥的制造主要趨于轉向更強調降低生產能耗，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。這些技術使得回轉窯變得短而且節(jié)省能源。這種研磨機一小時可以研磨出400噸的生料。
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