選煤相關外文資料及翻譯

1、<p><b>　　中文1770字</b></p><p>　　COAL PREPARATION</p><p>　　TABLE 7-14. Effect of Geometry and Concentration of Feed Solids on throughput for a 1/6-in, diam hydro cyclone cleaning 1

2、/4-in</p><p>　　Varying the distance between the bottom of the vortex finder and the hydro cyclone cone bottom. For example, the washed coal ash can be reduced by decreasing the diameter of the vortex finder,

3、 decreasing the length of the vortex finder, or increasing the diameter of the underflow orifice. Increasing feed-Solids content increases the specific gravity of separation and, therefore, washed coal yield and ash, whi

4、ch indicates the importance of maintaining a constant feed-solids content to preserve wa</p><p>　　Capacity is influenced by cyclone geometry, i.e., the sizes of the overflow, underflow, and inlet openings, a

5、nd by feed-solids content. The effects of these parameters is given in Table 7- 14.Increasing inlet pressure is a simple method of increasing capacity without changing hydro cyclone geometry, and washed yield and ash are

6、 not significantly affected. However, the penalty is increased pumping cost, and degradation of the coal. </p><p>　　Flow sheets</p><p>　　Soon after the hydro cyclone was developed, it became evi

7、dent that performance was inferior to nearly all other cleaning devices. Consequently, in an effort to improve performance, three two stage circuits, shown in Fig. 7~64, were developed. In the earliest two-stage circuit,

8、 called two-stage relearn or TSR, the refuse from a primary hydro cyclone is simply relearned in a secondary hydro cyclone, The overflows from the two hydro cyclones are recombined as the washed coal product, and the und

9、erf</p><p>　　Each of these circuits has advantages that depend upon the size and specific gravity compositions of the feed, as well as the required washed coal quality. The TSOR circuit is more effective in

10、recovering washed coal whereas the TSUR circuit is more effective in rejecting heavy impurity. The TSR circuit is most effective when the specific gravity of separation of the two hydro cyclones is similar. Conversely, t

11、he performance of TSOR and TSUR is improved by diverging the specific gravity of separ</p><p>　　Some plants using jigs to clean the coarse coal utilize hydro cyclones to improve performance on the finer size

12、s. One method is to relearn the underflow of the washed coal screen, commonly the 1/4-in.material, with hydro cyclones. Another method is to screen the raw coal at about this size and clean the undersize with hydro cyclo

13、nes.</p><p>　　Hydro cyclones have been used ahead of dense-medium cyclones to remove some of the low specific gravity coal and thereby reduce the amount of material sent to the dense-medium plant. The hydro

14、cyclones are adjusted to separate at a specific gravity of about 1.35 to 1.40. The advantage is that the capacity of the dense-medium cyclone plant can be smaller, thus reducing capital and operating costs.</p>&l

15、t;p>　　Hydro cyclone Performance</p><p>　　As mentioned previously, the quality of the washed coal and refuse products can be regulated by changing the diameters of the overflow and underflow orifices. Howe

16、ver from a performance standpoint, a ratio of overflow diameter to underflow diameter in a range of about 1.7 to 2 gives the best results. Performance at lower ratios is inferior. Also, the solids content in the feed to

17、primary and secondary hydro cyclones should range from 8 to 15 % (by weight). Outside this range, either above or bel</p><p>　　Separations obtained in a single hydro cyclone and two-stage circuits (TSR) are

18、shown by the distribution curves in Fig. 7-65. The sharpness of separation of the two-stage circuit is significantly superior to that of a single hydro cyclone. Also, the sharpness of separation of the two-stage circuit

19、is not nearly as sharp as the separations characteristic of a dense-medium cyclone. It follows then that hydro cyclones are not applicable for difficult-to-clean coal or separations at low specific gr</p><p>

20、;　　Hydro cyclones may be especially applicable for cleaning -30-mesh (0.6- mm) coal if the coal is not amenable to flotation. However, the Majority of US coals are easily cleaned by flotation. But if the coal is not amen

21、able to flotation because of a slime-coating problem or the coal is oxidized, then hydro cyclones may be a viable alternative. Also if fine pyrite is present in the feed, hydro cyclones are reported to be superior to flo

22、tation for lowering the sulfur content of the washed coal.</p><p>　　The coarser particles of an easy-to-clean coal with a top size of 1/4 or 3/8 in.(6.3 or 9.5 mm) can be cleaned about as efficiently in a tw

23、o-stage hydro cyclone circuit as on a concentrating table, but not as efficiently as in a feldspar jig. However, the concentrating table cleans the finer particles much more efficiently than the hydro cyclone. The distri

24、bution curves for a two-stage hydro cyclone circuit (TSR) and a concentrating table cleaning a 1/4-in (6.3mm*0) feed are shown in Fig. 7-66. </p><p>　　A relatively new separator, called the air-spared hydro

25、cyclone, has been developed and can be used to clean opal. It is essentially a porous cylinder without the usual conical section. Feed enters tangentially at the top and spirals downward. Air is introduced through the po

26、rous cylinder, and the air bubbles and flotation reagents along with the vortex effect the separation. Coal particles attach to the rising air bubbles and exit the top through a vortex.</p><p><b>　　選煤&

27、lt;/b></p><p>　　表7-14，給出了影響入料分選密度和粒度的處理量。旋流器直徑為1/4-in.</p><p><b>　　表7-14</b></p><p>　　改變旋流器溢流口和底流口的距離。例如，要降低分選精煤的灰分可以減小旋流器溢流口的距離，減小溢流管的長度，或者增大底流口的直徑。增大入料量會降低分選效率，因此，分

28、選精煤的產率和灰分的關系表明了保證恒定的入料量才能保證洗選精煤的質量。</p><p>　　處理量影響著旋流器的幾何尺寸，包括溢流口的尺寸，底流口的尺寸，入料口的尺寸和入料量。這些參數的影響如表7 – 14。改變入料壓力是一個改變旋流器參數的簡單方法，然而對改變精煤的產率和灰分的影響不顯著，況且會增加抽水成本，還會增加煤的泥化現象。</p><p><b>　　流程圖</b

29、></p><p>　　隨著旋流器的發(fā)展，很明顯它毫不遜色于其他所有的洗選設備。因此，為了提高性能，兩段分選的旋流器（如圖7-64）被開發(fā)了出來。最早的兩段分選旋流器叫第二段再選或者叫TSR，從第一段旋流器出來的產品只是簡單的在第二段再選，從兩段旋流器溢流口出來的煤被混合當作洗選精煤產品。從第二段旋流器底流出來的物料被視為洗選尾礦作為矸石。最近的有一種設備，一種從旋流器第二段出來的產品被循環(huán)作為第一段的入料

30、。在兩段旋流器的溢流循環(huán)，TSOR，這種從旋流器的第一段被作為調節(jié)產品所要求精煤，第二段作為調節(jié)尾礦中保證沒有錯配物。從旋流器第二段的溢流出來的物料包含本該進入到第二段旋流器底流的錯配物，所以返回到第一段旋流器進行再次循環(huán)洗選。在兩段旋流器底流循環(huán)，TSUR，這種從第一段旋流器的底流出來的物料被作為最終的尾礦矸石，第二段的底流出來的物料再次進入到第一段作為第一段的入料。從第二段溢流出來的產品被作為最終的洗選精煤產品。</p>

31、<p>　　上述的其中每個流程都有優(yōu)點，取決于入料的粒度組成，和所要求的精煤產品質量。TSOR流程能更有效地回收分選精煤，而TSUR流程更有效地排除重產物。當兩段旋流器分選的比重類似時TSR流程是最有效的流程。相反，TSOR和TSU</p><p>　　的性能取決于兩段旋流器的分流量。在目前，TSOR是應用的最為普遍的一種流程。有人提出一種改進的TSR流程是從第一段主選底流出來的物料被再次分選濃縮代

32、替第二段旋流器分選。</p><p>　　有一些廠用跳汰機分選塊煤，利用旋流器分選細粒的煤。一種方法是用煤用振動篩篩分的篩下物（通常1/4英寸）的煤用旋流器分選，另一種方法是用煤用振動篩篩分出粗粒煤，細粒度的煤用旋流器分選。</p><p>　　旋流器也被運用到重介質分選中去分選出一些含煤少的貧礦，以降低選煤廠重介質的消耗。旋流器可以調節(jié)的分選密度大概在1.35～1.40之間。這樣的優(yōu)點是

33、大大的降低了分選過程中所需重介質的體積，節(jié)約了資金和運營的成本。</p><p><b>　　水力旋流器性能</b></p><p>　　正如上文以前，對洗精煤產品質量和垃圾，可通過改變調節(jié)溢出和下溢口的直徑。但是從性能的角度來看，溢流直徑到底流直徑的比例范圍為約1.7至2為最好，較低的比率性能為低劣產品。此外，在原料中固體物含量，一段和二段水力旋流器應定為8至15％

34、（重量）。此范圍以外，高于或低于，性能將產生不利影響。分離獲得的水力旋流器和一個兩階段的電路（TSR）是由圖所示的分布曲線，兩個階段的電路分離清晰度明顯優(yōu)于單一的水力旋流器，另外，這兩個階段的電路分離清晰度幾乎沒有像重介質旋流器特點鮮明，由此得出結論，水力旋流器應用于難以清潔煤或低比重的適用，除非更，有效的再分選過程。此外，他們沒有合適的煤或者易碎的煤矸石顆粒板狀。</p><p>　　表7-15給出了詳細的兩個

35、階段（TSR）的水力旋流器的性能數據。這些數據表明，在一般的分離增加，分離小顆粒的清晰度的減少。水力旋流器可能會適合分選- 30目（0.6毫米）的煤，如果煤不浮選。然而，美國多數煤浮選煤很容易分選通過浮選。但是，如果煤炭，不受外界因為黏涂層問題浮選或煤被氧化，然后水力旋流器可能是一種可行的選擇。另外，如果細粒黃鐵礦是目前的原料，據報道水力旋流器，對于降低洗精煤的硫含量優(yōu)于浮選。一個易于清潔粗顆粒煤，有1 / 4或3 / 8英寸（6.3或

36、9.5毫米大小的粗顆粒頂部）可以被兩階段水力旋流器有效地清理，作為一個選礦臺，但沒有有效的長石跳臺。但是，集中清理的細小顆粒表比水力旋流器更有效。如圖7-66.所示：</p><p>　　一種相對較新的名為空氣旋流器的分選設備被研制出來并可用于分選蛋白石。它本質上是一個沒有通常錐形部分多孔圓筒。入料進入切向頂部并螺旋下降，空氣是透過多孔圓筒，氣泡和浮選劑隨著漩渦影響分選。煤顆粒附著在氣泡上升到漩渦的頂部。<