外文翻譯---波特蘭水泥的原料準(zhǔn)備

1、.外文資料翻譯Portland Cement Preparation of Raw Materials1. Crushing The raw materials as received from the mines are in lump form and have to be crushed before fine grinding. The size of the lumps would depend upon the raw material and the method of mining, so the size of the crushing equipment used woul

2、d depend primarily upon the size of the lumps received. In a modern cement factory, manufacturing 1000 to 2000 tonnes of cement per day, the limestone is mined by mechanical means and hence the size of individual pieces may be 1 meter or so. In smaller factories, the mining of limestone may be manua

3、l and the size of individual pieces may be 200 mm or so. Similarly, clay, shale, bauxite, laterite, sandstone, coal, gypsum, etc. may be received in sizes not larger than 300 mm.(a) Limestone Crushers: The requirement of limestone per day for a 2000 TPD factory may be about 2600 to 3000 TPD, for a 1

4、000 TPD factory 1300 to1500 TPD and for a 300 TPD factory 400 to 450 TPD. As the mining operation has to be carried out in daylight hours only, the crushing operation should also be carried out in the 10 or 12 hours of light per day. The capacity of a limestone crusher for a 2000 TPD factory may be

5、300 TPH, for a 1000 TPD factory 150 TPH and for a 300 TPD factory 50 TPH. The decision on the type of limestone crusher would depend upon the physical properties of the limestone; however, for smaller factories using manually mined limestone, single stage Hammer Crushers are most suitable; but for l

6、arger factories two stage crushing is always more economical and more efficient. The first stage may be a Jaw Crusher, Gyratory Crusher or Impact Crusher and the second stage a Hammer Crusher or Cone Crusher. If possible, a screen of suitable size may be introduced after the secondary crusher to all

7、ow only undersize to go for further processing while oversize is returned to the crusher. A typical flowsheet for a limestone crushing plant in a 2000 TPD factory may be.Dumpers-Feed Hopper with Laminated conveyor at the bottom 300 TPH Jaw Crusher (feed size 1000 mm - product size 200 mm ) 300 TPH H

8、ammer Crusher or Impact Crusher or Cone Crusher (feed size 200 mm - product size 20mm 300 THP Vibrating screen accepts minus 20 mm - oversize back to crusher.Proper dedusting arrangements must be made at the crushers, the vibrating screen and the transfer points and a Dust Collector with fan install

9、ed. Power consumed for the crushing operation may vary from 3 to 6 Kwh per tonne of limestone. (b) Other Crushers. Crushers required for crushing shale, gypsum, coal, etc. may be of suitable design, preferably Hammer Mills, and of suitable size. For the 2000 TPD factory requiring 10 % addition of sh

10、ale to the raw mix, using the dry process and using 6 % gypsum for cement grinding, the shale required would be about 3000 TPD, coal 4000 TPD and gypsum 100 TPD. The preferable size of the crushers would be 30 TPH, 50 TPH and 20 TPH respectively. The feed size may be specified minus 300 mm, and prod

11、uct size 20 or 25mm.2.Storage of Raw MaterialsLimestone in lump form is generally not stored at the factory, it is crushed as soon as it is received at the factory or even crushed at the mine itself and only crushed limestone is store at the factory. Shale or other corrective materials, coal and gyp

12、sum are generally stored in lump form as well as in crushed form. It would, therefore be advisable to have a common covered storage space for all types of crushed materials with proper partitions and proper reclaiming arrangements, Shale, gypsum, coal, etc., received in lump form, should be stored s

13、uitably and arrangements made to feed the same to the respective crushers mechanically. Two types of storage for crushed material are common: (a) crane gantry with Electric Overhead Travelling (EOT) cranes and (b) Storage bins with overhead feed belt conveyors and underground reclaiming belt conveyo

14、rs, the second alternative may be more economical both in first costs and operating costs. The latest development in the storage of crushed raw materials, especially for factories with annual capacities of 0.5 million tonnes or more, is the "Bed Blending System" in which crushed limestone

15、from different faces of the mines and correctives are spread in predetermined layers at one end and the material reclaimed with the help of cutter blades at the other end, so that a preblended raw mix of approximately the desired chemical composition is fed to the raw mill hoppers.the system can be

16、housed either in the open or under cover, depending upon the climatic conditions of the location. Lump materials are generally stored in the open and reclaimed with the help of Pay Loaders or Scraper Haulers or Bull Dozers.3.Fine GrindingIn the manufacture of Portland Cement types, the calcareous co

17、nstituent have to combine with the argillaceous constituents are ground and the more intimately they are mixed, the more efficient would be combination. If the limestone is of cement grade composition, the argillaceous constituents are intimately dis-seminated in the calcareous matrix, such a raw ma

18、terial can be ground coarse; but if the calcareous constituent is very pure and considerable amount of clay or shale has to be added, the raw mix must be ground much finer. A few tests carried out in a pilot plant can indicate the optimum degree of grinding required for a particular raw mix. It must

19、 be remembered that the raw materials fed to the grinding equipment are generally minus 20 mm and the product size may be 13±7% on 90 micron sieve. Intimate mixing is another important factor; the raw mix has to be brought to a very precise oxide composition, which in the manufacture of cement

20、is generally gauged determining the total carbonates (TC) by simple acid/alkali titration. For example, if at a factory the holding point of TC is 78%, the TC from batch to batch should not vary more than 78±0.1%, and this can be achieved only by thorough mixing.4.storage of Ground MaterialIn t

21、he wet process the ground slurry is stored either in silos or in basins with continuous mixing. The storage capacity should be 2 to 3 days' consumption for the factory. In the dry process, tall silos are used for storage of the dry raw meal. It is now the general practice that mixing silos or &q

22、uot;homogenising silos" are placed above the storage silos, so that the ready mixed and corrected raw mix is fed to the storage silos by gravity, result in a saving in power. The various methods of feeding the slurry and the dry raw meal to the burning equipment will be discussed in the next se

23、ction, dealing with burning operation.5.Coal GrindingAs coal has been considered a raw material, grinding of coal should also considered in this section. Coal has to be ground dry. Raw coal always contains 2% to 10% moisture; during the rainy season the moisture content always goes up, sometimes eve

24、n up to 15% to 20%. Therefore, coal has to be dried suitably before grinding. In early days rotary driers were used, but some forty years ago, mills were designed in which the coal could be dried and ground simultaneously with the help of hot air, in air swept ball mills. In separate drying and grin

25、ding systems the raw is dried in suitable driers with the help of hot air generated in an oil fired or coal fired or coal fired furnace; the spent air is vented to the atmosphere through suitable dust collectors. The dry coal is then ground, either in an open circuit coal mill in which the ground co

26、al is transported to the coal firing hopper with the help of a bucket elevator, other dry coal may be ground in an air swept close circuit mill, and air used to transport the ground coal to the cyclone over the coal firing hopper; the same air is used as primary air in the coal firing pipe. In a sim

27、ultaneous drying and grinding system, the front portion of the mill; fitted with lifters and chains, acts as the rotary drier and the back portion, filled with steel balls, acts as the closed circuit mill; hot air, either from the rotary kiln or from an auxiliary furnace, is used as air for drying a

28、nd transporting the coal. The spent air, in this case also, is used as primary air in the coal firing pipe. The power consumption in separate drying and grinding units may work out to 25 to 30 kW·h per tonne fine coal and in the simultaneous drying and grinding units to about 20 to 25 kW·h

29、 per tonne fine coal.6.Burning A mixture of pure lime and silica in the proportion of 2. 8:1 should give 100% tricalcium silicate on burning, but it will require a very prolonged heating at 1600 or more, to obtain a perfect combination. It is not possible to obtain such prolonged heating conditions

30、in actual plant practice; it is, therefore, necessary to add some fluxing materials to bring about the combination at a lower temperature and in a shorter time. Alumina, iron oxide and, to some extent, magnesia and alkalies present in the raw mix act as the fluxing agents. By judicious inclusion of

31、these oxides in the raw mix it is possible to shorten the reaction time to reasonable limits within the range of temperatures available in actual plant practice. In the process of burning in the manufacture of cement, the raw mix is first heated to about 100 where the moisture present in the dry raw

32、 meal or in the semi -dry process nodules or in the wet process slurry is removed. The dry raw mix is further heated and at about 400 to 500 the combined moisture present in the clay matter of the raw mix is dissociated and removed and magnesium carbonate, if present, is dissociated. On further heat

33、ing to about 900 the calcium carbonate (the main ingredient of the raw mix) is dissociated, carbon dioxide evolved and simultaneously combination between the lime (CaO) and the Silica (SiO2), alumina (Al2O3) and iron-oxide (Fe2O3) starts. Presumably, first all the FezO3 present in the raw mix and a

34、part of Al2O3 combine with lime to form C4AF at about 1200. This point may be termed as the start of the burning zone of the rotary kiln. The C4AF being the liquid form, the loose powdery mass starts becoming more coherent, and the movement of the material in the rotary kiln becomes more sluggish. A

35、t the same time, a part of the SiO2 present starts combining with CaO to form C2S. Then the remaining Al2O3 present combines with lime to form C3A, and now because the material has more liquids proper clinker nodule formation starts. As the mass passes further down the kiln, all the SiO2 present com

36、bines with lime (CaO) to form C2S and the remaining lime (CaO) starts combining with C2S to form C3S. This point may be called the beginning of the actual clinkering zone which extends to the point where practically all the lime present combines with C2S to form C3S and very little free lime is left

37、. At this point the clinker leaves the burning zone and cooling of the clinker starts. Clinker burning takes place in the above mentioned sequence in all the processes of burning, viz. , Long Dry Process Kiln, Long Wet Process Kiln, Short Dry Process kiln with suspension preheaters and Short Kilns w

38、ith great heat exchangers. Lime silicates (C2S and C3S) are the true cementations materials, C3S contributing towards early strength and C2S towards late strength, so the Process Chemist tries to obtain the highest possible C3S and lowest possible free lime in his clinker commensurate with: 波特蘭水泥的原料

39、準(zhǔn)備破碎作為從礦山得到的原料以塊狀形式（存在），必須在研磨之前被破碎。 塊狀的大小取決于原料和采礦的方法，因此，所用破碎設(shè)備的尺寸（規(guī)格）將主要地取決于收到的塊狀大小。在一個(gè)現(xiàn)代化的水泥工廠(chǎng),每天生產(chǎn)（日產(chǎn)）1000到2000噸的水泥，石灰石采用機(jī)械的方法（手段）挖掘，因此個(gè)別的塊大小可能達(dá)到1米左右。在較小的工廠(chǎng)，石灰石的采礦可能是人工的，個(gè)別塊的大小可能達(dá)到200毫米左右。同樣地,粘土、頁(yè)巖、（鋁）礬土、紅土（鐵礬土）、，沙巖、煤、石膏等，其大小一般不超過(guò)300毫米。(a)石灰石破碎：一個(gè)2000TPD的工廠(chǎng)每天石灰石的需求量可能是2600到3000TPD；一個(gè)1000TPD的工廠(chǎng)每天石灰

40、石的需求量可能是1300到1500TPD；一個(gè)300TPD的工廠(chǎng)每天石灰石的需求量可能是400到450TPD。由于采礦操作必須在白天進(jìn)行,破碎操作也應(yīng)該在白天的10或12個(gè)小時(shí)內(nèi)進(jìn)行。一個(gè)2000TPD的工廠(chǎng)石灰石破碎機(jī)的能力可能是300TPH；一個(gè)1000TPD的工廠(chǎng)是150 TPH；一個(gè)300TPD的工廠(chǎng)是50TPH。石灰石破碎機(jī)的選型取決于石灰石的物理性質(zhì)，然而，對(duì)于用人工挖掘石灰石的小型工廠(chǎng), 單段錘式破碎機(jī)是最適當(dāng)?shù)?，但?duì)于比較大的工廠(chǎng)，二級(jí)破碎總是更經(jīng)濟(jì)和更有效率，第一個(gè)階段可以是顎式破碎機(jī)、轉(zhuǎn)子破碎機(jī)或沖擊破碎機(jī)，第二個(gè)階段破碎為錘式破碎機(jī)或圓錐式破碎機(jī)。如果可能，適當(dāng)尺寸的篩子

41、應(yīng)該用于二級(jí)破碎以便只允許小于（篩孔）尺寸的物料通過(guò)而大塊物料繼續(xù)破碎。一個(gè)典型的2000 TPD石灰石破碎生產(chǎn)線(xiàn)流程應(yīng)該是：底部裝有薄板傳送帶的卸料斗；300TPH 顎式破碎機(jī)(原料大小1000毫米、 產(chǎn)品大小200 毫米)；300 TPH 錘式破碎機(jī)或沖擊破碎機(jī)或圓錐破碎機(jī)(原料大小200毫米、產(chǎn)品大小20 mm )；300THP振動(dòng)篩-允許小于20毫米通過(guò)太大的返回破碎機(jī)。破碎機(jī)、振動(dòng)篩和轉(zhuǎn)向點(diǎn)必須安排適當(dāng)?shù)某龎m，收塵器安裝有風(fēng)機(jī)。破碎作業(yè)的能耗變化很大，從3到6 Kwh/噸石灰石。（b）其它的破碎。頁(yè)巖、石膏和煤等的破碎必需使用破碎設(shè)備，使用錘式磨機(jī)及適當(dāng)?shù)拇笮。ㄒ?guī)格）可能是適當(dāng)?shù)脑O(shè)計(jì)

42、。對(duì)于2000 TPD的工廠(chǎng)，原料混合物中需要加入10%的頁(yè)巖，使用干法生產(chǎn)（工藝）以及水泥磨中加入6%石膏，頁(yè)巖 的需求量大約為300TPD、煤400TPD 和石膏100TPD。破碎機(jī)較好的大?。ㄒ?guī)格）將分別地是30TPH，50TPH和 20TPH，原料粒度規(guī)（指）定為小于300毫米，產(chǎn)品粒度為20或25 mm。2.原料的儲(chǔ)藏塊狀石灰石通常不在工廠(chǎng)儲(chǔ)存,一旦進(jìn)廠(chǎng)就立即被破碎，或者甚至在礦山本身就被破碎，在工廠(chǎng)只是儲(chǔ)藏。頁(yè)巖或其他的校正原料、煤和石膏通常最好以破碎過(guò)的塊狀形式儲(chǔ)存，因此，對(duì)所有類(lèi)型的破碎過(guò)的原料，最好有公共的帶有屋頂?shù)牟⒈贿m當(dāng)分割以及適當(dāng)取料-頁(yè)巖、手石膏、煤等的儲(chǔ)藏空間（聯(lián)合

43、堆棚），收到的塊狀（物料）將被巧妙的儲(chǔ)存和排列以使相同的物料去各自的破碎機(jī)械。破碎物料儲(chǔ)庫(kù)的兩種類(lèi)型通常是：(a)帶有電動(dòng)天車(chē)(EOT)的起重機(jī)，(b)帶有高空物料皮帶輸送機(jī)和地下取料皮帶輸送機(jī)的儲(chǔ)藏箱柜（儲(chǔ)庫(kù)）， 第二種選擇可能在第一費(fèi)用（基建費(fèi)用）和生產(chǎn)費(fèi)用更經(jīng)濟(jì)。在破碎的原料儲(chǔ)藏方面的最新發(fā)展-尤其是年產(chǎn)五十萬(wàn)噸或更多的工廠(chǎng), 是“混合床系統(tǒng)（預(yù)配料均化系統(tǒng)）”-從不同礦區(qū)來(lái)的破碎過(guò)的石灰石和校正原料，從一端以預(yù)先確定的層鋪開(kāi)，在另一端借助于刀片取料, 以便使預(yù)混料近似于需要的化學(xué)成分被喂到生料磨喂料斗。根據(jù)當(dāng)?shù)貧夂?，該系統(tǒng)既可有廠(chǎng)房，也可露天或搭棚。塊狀物料通常露天儲(chǔ)存并且借助于裝載機(jī)

44、或鏟車(chē)或推土機(jī)取料。3.粉磨在波特蘭類(lèi)型水泥的生產(chǎn)中，石灰質(zhì)成份必須與粘土質(zhì)成份聯(lián)合粉并且更密切地混合，（成分）差別越大越要混合。如果石灰石是水泥主要成分，粘土成分密切地分布在石灰質(zhì)的點(diǎn)陣中，這樣的原料粉磨可能是地粗糙的，但是如果石灰質(zhì)成份是非常純的并且相當(dāng)量的泥土或頁(yè)巖必須加入, 混合原料必須充分粉磨。在一個(gè)試驗(yàn)工廠(chǎng)進(jìn)行的一些測(cè)試表明了詳細(xì)的原料混合所需要的最適宜的研磨程度。供應(yīng)給磨機(jī)的原料一般小于20毫米、產(chǎn)品細(xì)度應(yīng)該是90微米篩子的篩余為13±7%-這必須被記住。密切的混合是另一個(gè)重要因素，原料的混合不得不帶進(jìn)大量氧化物成分，在水泥的生產(chǎn)中通常通過(guò)簡(jiǎn)單的酸/堿滴定測(cè)量確定總碳酸鹽(TC)。 舉例來(lái)說(shuō)，如果在一間工廠(chǎng)把握的TC是78%，每一批的TC變化量不應(yīng)該超過(guò)78±0.1% ，而且這可能只有通過(guò)完全的混合來(lái)實(shí)現(xiàn)。4.生料儲(chǔ)存在濕法生產(chǎn)（工藝）中，粉磨的生料漿既可儲(chǔ)存在生料（料漿）庫(kù)和帶連續(xù)混合的料漿池中，儲(chǔ)存能力應(yīng)該是工廠(chǎng)2到3天的消費(fèi)量。在干法生產(chǎn)（工藝）中，高大的生料庫(kù)用于干生料的儲(chǔ)存，設(shè)置在儲(chǔ)存庫(kù)之上的混合庫(kù)或“均化庫(kù)”是目前通常采用的，以便預(yù)先混合并得到調(diào)整的混合生料通過(guò)重力被喂入到儲(chǔ)存庫(kù)，以節(jié)省動(dòng)力