1728_齒輥破碎機(jī),破碎 外文資料翻譯題目： 齒輥破碎機(jī)系 別 航空與機(jī)械工程系專業(yè)名稱 機(jī)械設(shè)計(jì)制造及自動(dòng)化班級(jí)學(xué)號(hào) 088105439學(xué)生姓名 朱芊全指導(dǎo)教師 封立耀二 O 一二 年 三 月 學(xué)士學(xué)位論文原創(chuàng)性聲明本人聲明，所呈交的論文是本人在導(dǎo)師的指導(dǎo)下獨(dú)立完成的研究成果。除了文中特別加以標(biāo)注引用的內(nèi)容外，本論文不包含法律意義上已屬于他人的任何形式的研究成果,也不包含本人已用于其他學(xué)位申請(qǐng)的論文或成果。對(duì)本文的研究作出重要貢獻(xiàn)的個(gè)人和集體，均已在文中以明確方式表明。本人完全意識(shí)到本聲明的法律后果由本人承擔(dān)。作者簽名： 日期：學(xué)位論文版權(quán)使用授權(quán)書(shū)本學(xué)位論文作者完全了解學(xué)校有關(guān)保留、使用學(xué)位論文的規(guī)定，同意學(xué)校保留并向國(guó)家有關(guān)部門(mén)或機(jī)構(gòu)送交論文的復(fù)印件和電子版，允許論文被查閱和借閱。本人授權(quán)南昌航空大學(xué)科技學(xué)院可以將本論文的全部或部分內(nèi)容編入有關(guān)數(shù)據(jù)庫(kù)進(jìn)行檢索，可以采用影印、縮印或掃描等復(fù)制手段保存和匯編本學(xué)位論文。作者簽名： 日期：導(dǎo)師簽名： 日期：中文譯文摘要低的破碎比和高的磨損率是與傳統(tǒng)的破碎機(jī)相聯(lián)系的很常見(jiàn)的兩個(gè)特性。因?yàn)檫@點(diǎn)，在礦石處理流程的應(yīng)用中，很少考慮到它們，并且忽略了很多它們的優(yōu)點(diǎn)。本文描述了一個(gè)已被發(fā)展起來(lái)的新穎的對(duì)輥破碎機(jī)，旨在提出這些論點(diǎn)。作為 NCRC,這種新式破碎機(jī)結(jié)合了兩個(gè)輥筒，它們由一個(gè)交替布置的平面和一個(gè)凸的或者凹的表面組成。這種獨(dú)特的輥筒外形提高了嚙合角，使 NCRC 可以達(dá)到比傳統(tǒng)輥式破碎機(jī)更高的破碎比。用一個(gè)模型樣機(jī)做的試驗(yàn)表明：即使對(duì)于非常硬的礦石，破碎比任可以超過(guò) 10。另外，既然在 NCRC 的破碎處理中結(jié)合了輥式和顎式破碎機(jī)的作用，那就有一種可能：那種新的輪廓會(huì)帶來(lái)輥?zhàn)幽p率的降低。關(guān)鍵字：介紹傳統(tǒng)的輥筒破碎機(jī)因?yàn)榫哂袔讉€(gè)缺陷而導(dǎo)致了其在礦石處理應(yīng)用中的不受歡迎。尤其是當(dāng)與其它的一些破碎機(jī)比起來(lái)，諸如圓錐破碎機(jī)等，它們的低破碎比（一般局限在 3 以內(nèi)）和高的磨損率使它們沒(méi)有吸引力。然而，從礦石處理這一點(diǎn)來(lái)說(shuō)，輥筒破碎機(jī)有一些非?？扇〉奶攸c(diǎn)：輥筒破碎機(jī)的相對(duì)穩(wěn)定的操作寬度可以很好控制產(chǎn)物粒度。彈簧承重的輥?zhàn)拥氖褂檬惯@些機(jī)器容許不可破碎的物料（諸如夾雜金屬等） 。另外，輥筒破碎機(jī)是這樣工作的：將物料牽引至輥?zhàn)又g的擠壓區(qū)而不是象圓錐和顎式破碎機(jī)那樣依靠重力。這產(chǎn)生了一個(gè)連續(xù)的破碎周期，避免了高通過(guò)率，同時(shí)也使破碎機(jī)可處理潮濕的和膠粘的物料。NCRC 是一種新穎的破碎機(jī)，發(fā)明于澳大利亞西部大學(xué)，為得是提出一些與傳統(tǒng)輥筒破碎機(jī)相聯(lián)系的一些問(wèn)題。新的破碎機(jī)結(jié)合了兩個(gè)輥?zhàn)?，由間隔布置的平面和凸的或者凹的表面組成。這種獨(dú)特的輥?zhàn)虞喞岣吡藝Ш辖?，?NCRC可達(dá)到比傳統(tǒng)輥筒破碎機(jī)更高的破碎比。用一個(gè)模型樣機(jī)的初步試驗(yàn)已表明：即使非常硬的物料，超過(guò) 10 的破碎比也可以實(shí)現(xiàn)。這些初期的發(fā)現(xiàn)是通過(guò)單一顆粒進(jìn)給而獲得的，在破碎中沒(méi)有顯著的物塊間的相互作用。目前的工作在NCRC 中用多物塊試驗(yàn)延伸了現(xiàn)存的結(jié)果。同時(shí)也顧及了各種其他因素：影響NCRC 特性和探索 NCRC 在選礦處理中使用效率。操作原理嚙合角是影響輥筒破碎機(jī)性能的重要因素之一。小的嚙合角是有利的，因?yàn)樗鼈冊(cè)龃罅宋飰K被輥筒抓住的可能性。對(duì)于一個(gè)給定的入料粒度和輥隙，傳統(tǒng)的輥筒破碎機(jī)的嚙合角受限于輥筒的尺寸。NCRC 試圖通過(guò)有特殊輪廓的輥筒克服這種限制，這種輪廓提高了輥筒在一轉(zhuǎn)中變化點(diǎn)的嚙合角。至于嚙合角，在選擇輥面時(shí)，很多其他的因素，包括變化的輥隙，破碎的方式都考慮了。最終 NCRC 輥筒形狀如圖 1 所示。其中一個(gè)輥?zhàn)佑砷g隔布置的平面和凸面組成，而另一個(gè)是由間隔布置的平面和凹面組成。NCRC 輥筒的形狀導(dǎo)致了幾個(gè)獨(dú)特的特點(diǎn)。其中最重要的就是在輥筒轉(zhuǎn)動(dòng)時(shí)，對(duì)于一個(gè)給定物塊粒度和輥隙，NCRC 所產(chǎn)生的嚙合角將不再保持穩(wěn)定。時(shí)而嚙合角比相同尺寸的圓柱輥筒低很多，時(shí)而高很多。輥?zhàn)愚D(zhuǎn)動(dòng)中嚙合角的實(shí)際變化量超過(guò) 60 度，如圖 2 所示，圖 2 也表示了相同情況下，可相比尺寸的圓柱輥筒破碎機(jī)所產(chǎn)生的嚙合角。這些嚙合角是對(duì)一個(gè)直徑為 25 毫米的圓形物塊放在輥徑大約 200 毫米、最小輥隙 1 毫米的輥筒間計(jì)算出來(lái)的。這個(gè)例子可以用來(lái)描述使用非圓柱輥筒的潛在優(yōu)點(diǎn)。為了抓住物塊，通常嚙合角不超過(guò) 25 度。因此，圓柱輥筒破碎機(jī)將一直夾不住這個(gè)物塊，因?yàn)槠鋵?shí)際嚙合角一直穩(wěn)定在 52度。然而，在輥筒轉(zhuǎn)過(guò) 60 度時(shí)，NCRC 的嚙合角降至 25 度以下。這意味著輥筒每轉(zhuǎn)過(guò)一轉(zhuǎn)，非圓柱輥筒破碎機(jī)可能有 6 次夾住物塊。試驗(yàn)過(guò)程N(yùn)CRC 的實(shí)驗(yàn)室模型由兩個(gè)輥筒部件組成，每一個(gè)由發(fā)動(dòng)機(jī)、齒輪箱和有形輥筒組成。兩個(gè)部件都安置在線性軸承上，其有效支持任何垂直部件的力，同時(shí)保證其水平運(yùn)動(dòng)。一個(gè)輥筒部件水平固定，而另一個(gè)通過(guò)壓縮彈簧限制，壓縮彈簧使輥筒抵抗一個(gè)變化的水平載荷?？蓜?dòng)輥筒上的預(yù)載荷可被調(diào)整直至最大值 20 千牛。驅(qū)動(dòng)輥筒的兩個(gè)電動(dòng)機(jī)通過(guò)一個(gè)變化的速度控制器實(shí)現(xiàn)電同步，速度控制器使輥速連續(xù)變化直至 14 轉(zhuǎn)每秒（大概 0.14 米每秒的線速度） 。輥筒有一個(gè) 188 毫米的中心距，100 毫米寬。兩個(gè)驅(qū)動(dòng)軸都裝有應(yīng)變規(guī)，用以測(cè)量輥筒扭矩。附加的傳感器用以測(cè)量固定輥筒的水平力和輥隙。NCRC 的邊上裝有透明玻璃以便于在運(yùn)行是觀察破碎區(qū)域，同時(shí)也使破碎流程得以用數(shù)碼相機(jī)進(jìn)行紀(jì)錄。試驗(yàn)進(jìn)行于幾種巖石，包括花崗巖、閃長(zhǎng)巖、礦石、采石場(chǎng)棄石和混凝土?；◢弾r和混凝土各取自商業(yè)性的采石場(chǎng)，前者先破碎、成形，而后者是爆炸的巖石。第一種礦石樣品是 SAG 采石場(chǎng)進(jìn)料，取于諾曼底煤礦的 GGO，采石場(chǎng)棄石取于 KAGMM 煤礦。采石場(chǎng)棄石含有直徑直至 18 毫米的金屬顆粒，它們來(lái)自于經(jīng)反復(fù)磨削和破碎的介質(zhì)?；炷劣蓤A柱體樣品（直徑 25 毫米、高 25 毫米）組成，它們根據(jù)澳大利亞的有關(guān)標(biāo)準(zhǔn)制備。不受限制的單軸壓力測(cè)試進(jìn)行于礦山樣本（直徑 25 毫米、高 25 毫米） ，取于大量的礦石。結(jié)果表明：對(duì)于制備混凝土的強(qiáng)范圍從 60 兆帕直至 GG 礦石樣品的 260 兆帕。起初，所有的樣品都通過(guò)一個(gè) 37.5 毫米的過(guò)濾器去處任何粒度過(guò)大的物塊。低于粒度要求的礦石被取樣，并且過(guò)濾以決定入料粒度分布。在 NCRC 中每一個(gè)試驗(yàn)大約破碎 2500 克樣品。這種樣品粒度基于統(tǒng)計(jì)測(cè)試進(jìn)行選擇，那些統(tǒng)計(jì)測(cè)試表明： 為了估計(jì)百分之八十的通過(guò)率在正負(fù) 0.1 毫米范圍內(nèi)的百分之九十五的可靠度至少需要破碎 2000 克樣品。選擇并振動(dòng)產(chǎn)品使其 10 次掉于過(guò)濾器下，使用一個(gè)標(biāo)準(zhǔn)的干的或濕的過(guò)濾方法以決定產(chǎn)品粒度分布。對(duì)于每一次試驗(yàn)，子樣品中的兩個(gè)被最先濾掉。如果產(chǎn)品粒度有任何顯著的不同，額外的子樣品將被濾掉。使用 NCRC 進(jìn)行大量的破碎試驗(yàn)以決定各種變化的參數(shù)的效果，參數(shù)包括：輥隙、輥上作用力、入料粒度和單個(gè)或多個(gè)物料進(jìn)給。因?yàn)榍懊娴脑囼?yàn)以得出輥速對(duì)產(chǎn)品粒度分布影響很小，所以將輥速設(shè)定在最大值且前面兩個(gè)試驗(yàn)之間不變。應(yīng)該指出的是：輥隙設(shè)置引用提及的最小輥隙。因?yàn)檩佂驳姆菆A柱體形，實(shí)際輥隙在設(shè)置的最小值以上的 1.7 毫米范圍內(nèi)變化（例：一個(gè) 1 毫米的輥隙設(shè)置值其意味著輥隙為 1-2.7 毫米） 。結(jié)果入料所有破碎設(shè)備的性能都依賴破碎物料的種類。在這方面，NCRC 沒(méi)有什么不同。在 NCRC 中破碎較軟物料可產(chǎn)生低于較硬物料 p80 的碎強(qiáng)。圖 4 所示是在NCRC 中在相似條件下破碎幾種不同物料時(shí)得到的產(chǎn)物粒度分布。有趣的是，除了備制混凝土樣品外，從各種不同的物料中，p80 碎強(qiáng)的獲得也相當(dāng)一致。結(jié)果反映：利用 NCRC 可獲得對(duì)產(chǎn)物粒度分布的控制程度。多入料物塊前面在 NCRC 上做的試驗(yàn)僅使用單入料物塊，很少或沒(méi)有物塊間的相互作用。雖然很有效，但與這種破碎方式相聯(lián)系的低的通過(guò)率不適合于實(shí)際應(yīng)用。因此，決定連續(xù)進(jìn)給對(duì)最終產(chǎn)品粒度分布的影響是有必要的。在這些測(cè)試中，連續(xù)供應(yīng)以保持足夠的物料以達(dá)到輥?lái)?。圖 5 顯示，連續(xù)進(jìn)給 NCRC 對(duì)諾曼底礦石產(chǎn)物粒度分布的影響。這些結(jié)果好像表明了使用連續(xù)（多物塊）進(jìn)給在 p80 碎強(qiáng)上的一個(gè)輕微的增加，然而變化太小以致其沒(méi)有統(tǒng)計(jì)學(xué)意義。相似地，對(duì)于連續(xù)進(jìn)給試驗(yàn)，產(chǎn)物粒度分布表明了一個(gè)較好結(jié)果，但實(shí)際上區(qū)別是微不足道的。如圖 6 所示，用花崗巖樣品使用不同的兩個(gè)輥隙進(jìn)行了相似的試驗(yàn)。又一次，在單個(gè)和多個(gè)物塊測(cè)試間無(wú)變化。毫不夸張地，更大的輥隙、更小的破碎程度（物料間的相互作用） ，區(qū)別將更不明顯。所有的這些測(cè)試好像表明連續(xù)進(jìn)給對(duì) NCRC 的性能影響極小。然而，意識(shí)到在這些試驗(yàn)中用的進(jìn)給物料在很小的范圍內(nèi)波動(dòng)是重要的，如圖 6（諾曼底試驗(yàn)的進(jìn)給物塊甚至更一致）所示進(jìn)給物塊粒度分布。進(jìn)給物塊粒度的一致性導(dǎo)致了大量的自由空間，允許破碎腔內(nèi)破碎礦石的增多，因此限制了物塊間的相互作用。有一寬廣物塊粒度分布（尤其是較小的粒度范圍）的帶礦石的 NCRC 的真的“卡死”進(jìn)給可能在破碎區(qū)域產(chǎn)生大得多的壓力。既然 NCRC 不是作為“高壓力破碎輥”而設(shè)計(jì)的，在這些情況下，更多的過(guò)大物塊將從兩輥間通過(guò)。輥隙象傳統(tǒng)的輥筒破碎機(jī)一樣，NCRC 的輥隙設(shè)置對(duì)產(chǎn)品粒度分布和破碎機(jī)通過(guò)率有直接影響。圖 7 展示了以三種不同輥隙破碎 AG 礦石（廢棄礦石）時(shí)的最終產(chǎn)物粒度分布。針對(duì)輥隙從這張圖中標(biāo)出 80 值產(chǎn)生一線性關(guān)系，如圖 p8 所示。如前解釋所述，NCRC 的實(shí)際輥隙將隨著一轉(zhuǎn)而變化。這一變化補(bǔ)償了具體的輥隙設(shè)置和取于破碎試驗(yàn)中的產(chǎn)物百分之八十通過(guò)率間的差別。圖 8 顯示了輥隙對(duì)破碎機(jī)通過(guò)率的影響并給出了用 NCRC 的試驗(yàn)?zāi)Ｐ偷玫降钠扑槁?。輥?dòng)力NCRC 是利用煤塊間的相互作用實(shí)現(xiàn)破碎機(jī)而設(shè)計(jì)的，這種破碎主要是通過(guò)直接折斷輥間物塊。因此，輥動(dòng)力僅需足夠大以克服輥面間物塊的復(fù)合力。如果輥動(dòng)力不夠大，那么礦石塊將分開(kāi)輥筒，從而過(guò)粒度物塊將落下。增大輥動(dòng)力以減小輥筒分離傾向以更好控制產(chǎn)物粒度。然而，一旦達(dá)到限制輥動(dòng)力（決定于被破碎物料的粒度和種類） ，輥動(dòng)力的任何進(jìn)一步增加都不能提高輥筒破碎機(jī)的性能。這由圖 9 可得證，顯示了 25-31 毫米的花崗巖入料，大約 16-18 千牛的輥動(dòng)力去控制產(chǎn)物粒度。如果輥動(dòng)力降至低于這一水平，雖然 p80 產(chǎn)物有一瞬間的增加，使用更大的輥動(dòng)力對(duì)產(chǎn)物粒度僅有很小影響。入料粒度分布和前面提及的一樣，入料粒度分布對(duì)破碎腔內(nèi)產(chǎn)生的壓力有明顯影響。有更細(xì)的入料粒度分布的礦石更趨向于“卡死” NCRC，降低破碎機(jī)的效率。然而，只要所產(chǎn)生的壓力不超過(guò) NCRC，不考慮入料粒度維持在一個(gè)相對(duì)穩(wěn)定的操作間隙。因此，產(chǎn)物粒度分布也將不依賴于入料粒度分布。如圖 10 所描述的，顯示了使用相同的設(shè)備但不同的粒度分布的入料的兩個(gè)破碎機(jī)試驗(yàn)的結(jié)果。在這個(gè)例子中，NCRC 將較粗糙的礦石從 80 的 34 毫米破碎至 80 的 3.0 毫米（破碎比11：1） ，同時(shí)較細(xì)的礦石從 80 的 18 毫米破碎至 80 的 3.4 毫米（破碎比 5：1） 。這些結(jié)果表明，使用有形輥筒的缺點(diǎn)減少，同時(shí)，入料粒度和輥筒尺寸的比例在減小。另一方面，為了達(dá)到較高的破碎比，入料塊度必須足夠大以利用 NCRC產(chǎn)生高的嚙合角的優(yōu)點(diǎn)。廢棄礦石一些磨礦流程使用往復(fù)或石子破碎機(jī)（例如圓錐破碎機(jī)）去處理那些取自于選礦廠和發(fā)現(xiàn)難于破碎（廢棄礦石）的物料。廢棄礦石常含有壞的或破碎的磨粒，常見(jiàn)于往復(fù)破碎機(jī)中。因此，對(duì)于一個(gè)石子破碎機(jī)，不可破碎的公差是一個(gè)有意義的特性。NCRC 看上去完美地適合于這一應(yīng)用，既然其中一個(gè)輥筒能產(chǎn)生屈服以讓不可破碎的物料通過(guò)。圖 11 所示的產(chǎn)物粒度分布取自于 NCRC 處理廢棄礦石。對(duì)兩個(gè)結(jié)果都使用相同的設(shè)備和入料粒度，然而，使用去處磨粒的礦石進(jìn)行其中一個(gè)試驗(yàn)。和預(yù)料的一樣，NCRC 可以處理含有未進(jìn)經(jīng) INCIDENT 的入料礦石。然而，既然一個(gè)輥筒為了讓磨粒通過(guò)而經(jīng)常移動(dòng)，大量的未經(jīng)破碎的過(guò)粒度物塊可以通過(guò)輥隙。結(jié)果，這種入料粒度的產(chǎn)物粒度分布顯示：對(duì)于更大的物塊粒度的變化和P80 值從 4 毫米增至 4.7 毫米。盡管如此， NCRC 仍可以達(dá)到差不多 4：1 的破碎比。磨損雖然沒(méi)有對(duì) NCRC 做具體的測(cè)試以決定磨損率，但為了試著了解破碎機(jī)理用高速錄像機(jī)紀(jì)錄了很多破碎試驗(yàn)。通過(guò)觀察輥筒間被破碎物塊，輥筒的部分區(qū)域好像受高磨損，并且得出一些主觀結(jié)論：這種磨損對(duì) NCRC 的性能有影響，這些都是可能的。毫不夸張地，所顯示的高磨損的首要區(qū)域是平的和凹的過(guò)渡表面。令人驚訝的是，這種邊緣在產(chǎn)生提高的嚙合角方面不起重要作用。NCRC 的性能不應(yīng)該直接受這邊磨損的影響，因?yàn)樗鼘?shí)際上是平的和凸的表面的過(guò)渡區(qū)域（在輥筒的對(duì)面） ，導(dǎo)致了減小的嚙合角。 第 1 頁(yè) 翻譯英文原文COMMINUTION IN A NON-CYLINDRICAL ROLL CRUSHER*P. VELLETRI ~ and D.M. WEEDON ~~[ Dept. of Mechanical & Materials Engineering, University of Western Australia, 35 Stirling Hwv,Crawley 6009, Australia. E-mail piero@mech.uwa.edu.au§ Faculty of Engineering and Physical Systems, Central Queensland University, PO Box 1!:;19,Gladstone, Qld. 4680, Australia(Received 3 May 2001; accepted 4 September 2001)ABSTRACTLow reduction ratios and high wear rates are the two characteristics ntost commonh" associated with conventional roll crushers. Because of this, roll crushers are not often considered Jor use in mineral processing circuits, attd many of their advantages are being largely overlooked. This paper describes a novel roll crusher that has been developed ipt order to address these issues.Relbrred to as the NCRC (Non-Cylindrical Roll Crusher), the new crusher incorporates two rolls comprised qf an alternating arrangement of platte attd convex or concave su@wes. These unique roll prqfiles improve the angle qf nip, enabling the NCRC to achieve higher reduction ratios than conventional roll crushers. Tests with a model prototype have indicated thar evell fi)r very hard ores, reduction ratios exceeding lO:l can be attained. In addition, since the comminution process in the NCRC combines the actions of roll arM jaw crushers there is a possibili O' that the new profiles may lead to reduced roll wear rates. ? 2001 Elsevier Science Ltd. All rights reserved.Keywords: Comminution; crushingINTRODUCTIONConventional roll crushers suffer from several disadvantages that have lcd to their lack of popularity in mineral processing applications. In particular, their low reduction ratios (typically limited to about 3:1) and high wear rates make them unattractive when compared to other types of comminution equipment, such ascone crushers. There are, however, some characteristics of roll crushers that are very desirable from a mineral processing point of view. The relatively constant operating gap in a roll crusher gives good control over product size. The use of spring-loaded rolls make these machines tolerant to uncrushable material (such as tramp metal). In addition, roll crushers work by drawing material into the compression region between the rolls and do not rely on gravitational feeci ~like cone and jaw crushers. This generates a continuous crushing cycle, which yields 第 2 頁(yè) high throughput rates and also makes the crusher capable of processing wet and sticky ore. The NCRC is a novel roll crusher that has been dcveloped at the University of Western Australia in ordcr to address some of the problems associated with conventional roll crushers. The new crusher incorporates tworolls comprised of an alternating arrangement of plane and convex or concave surfaccs. Thcse unique roll profiles improve the angle of nip, enabling the NCRC to achieve higher reduction ratios than conventional roll crushers. Preliminary tests with a model prototype have indicated that, even for very hard oics,reduction ratios exceeding 10:I can be attained (Vellelri and Weedon, 2000). These initial findings were obtained for single particle feed. where there is no significant interaction between particles during comminution. The current work extends the existing results bv examining inulti-particle comminution inthe NCRC. It also looks at various othcr factors that influencc the perli~rmance of the NCRC and exploresthe effectiveness of using the NCRC for the processing of mill scats.PRINCIPLE OF OPERATIONThe angle of nip is one of the main lectors effccting the performance of a roll crusher. Smaller nip anglesare beneficial since they increase tl~e likelihood of parlictes bcing grabbed and crushed by lhe rolls. For agiven feed size and roll gap, the nip angle in a conventional rtHl crusher is limited by the size of thc rolls.The NCRC attempts to overcome this limitation through the use of profiled rolls, which improve the angleof nip at various points during one cycle (or revolution) of the rolls. In addition to the nip angle, a numberof other factors including variation m roll gap and mode of commmution were considered when selectingIlle roll profiles. The final shapes of the NCRC rolls are shown in Figure I. One of the rolls consists {sI analternating arrangement of plane and convex surfaces, while the other is formed from an alternatingarrangement of phme and concave surlaccs. 第 3 頁(yè) The shape of the rolls on the NCRC result in several unique characteristics. Tile most important is that, lk)ra given particle size and roll gap, the nip angle generated m the NCRC will not remain constant as the rollsrotate. There will be times when the nip angle is much lower than it would be for the same sized cylindricalrolls and times when it will be much highcr. The actual variation in nip angle over a 60 degree roll rotationis illustrated in Figure 2, which also shows the nip angle generated under similar conditions m a cylindricalroll crusher of comparable size. These nip angles were calculated for a 25ram diameter circular particlebetween roll of approximately 200ram diameter set at a I mm minimum gap. This example can be used toillustrate the potential advantage of using non-cylindrical rolls. In order for a particle to be gripped, thcangle of nip should normally not exceed 25 ° . Thus, the cylindrical roll crusher would never nip thisparticle, since the actual nip angle remains constant at approximately 52 °. The nip angle generated by theNCRC, however, tidls below 25 ° once as the rolls rotate by (~0 degrees. This means that the non-cylindricalrolls have a possibility of nipping the particlc 6 times during one roll rewHution.EXPERIMENTAL PROCEDUREThe laboratory scale prototype of the NCRC (Figure 3) consists of two roll units, each comprising a motor,gearbox and profiled roll. Both units are mounted on linear bearings, which effectively support any verticalcomponcnt of force while enabling horizontal motion. One roll unit is horizontally fixed while the other isrestrained via a compression spring, which allows it to resist a varying degree of horizontal load. 第 4 頁(yè) The pre-load on the movable roll can be adjusted up to a maximum of 20kN. The two motors that drive therolls are electronically synchronised through a variable speed controller, enabling the roll speed to becontinuously varied up to 14 rpm (approximately 0.14 m/s surface speed). The rolls have a centre-to-centredistance ~,at zero gap setting) of I88mm and a width of 100mm. Both drive shafts are instrumented withstrain gauges to enable the roll torque to be measured. Additional sensors are provided to measure thehorizontal force on the stationary roll and the gap between the rolls. Clear glass is fitted to the sides of theNCRC to facilitate viewing of the crushing zonc during operation and also allows the crushing sequence tobc recorded using a high-speed digital camera. 第 5 頁(yè) Tests were performed on several types of rocks including granite, diorite, mineral ore, mill scats andconcrete. The granite and diorite were obtained from separate commercial quarries; the former had beenpre-crushed and sized, while the latter was as-blasted rock. The first of the ore samples was SAG mill feedobtained from Normandy Mining's Golden Grove operations, while the mill scats were obtained fromAurora Gold's Mt Muro mine site in central Kalimantan. The mill scats included metal particles of up to18ram diameter from worn and broken grinding media. The concrete consisted of cylindrical samples(25mm diameter by 25ram high) that were prepared in the laboratory in accordance with the relevantAustralian Standards. Unconfined uniaxial compression tests were performed on core samples (25mmdiameter by 25mm high) taken from a number of the ores. The results indicated strength ranging from 60MPa for the prepared concrete up to 260 MPa for the Golden Grove ore samples.All of the samples were initially passed through a 37.5mm sieve to remove any oversized particles. Theundersized ore was then sampled and sieved to determine the feed size distribution. For each trialapproximately 2500g of sample was crushed in the NCRC. This sample size was chosen on the basis ofstatistical tests, which indicated that at least 2000g of sample needed to be crushed in order to estimate theproduct P80 to within +0.1ram with 95% confidence. The product was collected and riffled into ten subsamples,and a standard wet/dry sieving method was then used to determine the product size distribution.For each trial, two of the sub-samples were initially sieved. Additional sub-samples were sieved if therewere any significant differences in the resulting product size distributions.A number of comminution tests were conducted using the NCRC to determine the effects of various 第 6 頁(yè) parameters including roll gap, roll force, feed size, and the effect of single and multi-particle feed. The rollspeed was set at maximum and was not varied between trials as previous experiments had concluded thatthere was little effect of roll speed on product size distribution. It should be noted that the roll gap settingsquoted refer to the minimum roll gap. Due to the non-cylindrical shape of the rolls, the actual roll gap willvary up to 1.7 mm above the minimum setting (ie: a roll gap selling of l mm actually means 1-2.7mm rollgap).RESULTSFeed materialThe performance of all comminution equipment is dependent on the type of material being crushed. In thisrespect, the NCRC is no different. Softer materials crushed in the NCRC yield a lower P80 than hardermaterials. Figure 4 shows the product size distribution obtained when several different materials werecrushed under similar conditions in the NCRC. It is interesting to note that apart from the prepared concretesamples, the P80 values obtained from the various materials were fairly consistent. These results reflect thedegree of control over product size distribution that can be obtained with the NCRC.Multiple feed particlesPrevious trials with the NCRC were conducted using only single feed particles where there was little or nointeraction between particles. Although very effective, the low throughput rates associated with this modeof comminution makes it unsuitable for practical applications. Therefore it was necessary to determine theeffect that a continuous feed would have to the resulting product size distribution. In these tests, the NCRCwas continuously supplied with feed to maintain a bed of material level with the top of the rolls. Figure 5shows the effect that continuous feed to the NCRC had on the product size distribution for the NormandyOre. These results seem to show a slight increase in P80 with continuous (multi-particle) feed, however theshift is so small as to make it statistically insignificant. Similarly, the product size distributions would seemto indicate a larger proportion of fines for the continuously fed trial, but the actual difference is negligible.Similar trials were also conducted with the granite samples using two different roll gaps, as shown inFigure 6. Once again there was little variation between the single and multi-particle tests. Not surprisingly,the difference was even less significant at the larger roll gap, where the degree of comminution (and henceinteraction between particles) is smaller. 第 7 頁(yè) All of these tests would seem to indicate that continuous feeding has minimal effect on the performance ofthe NCRC. However, it is important to realise that the feed particles used in these trials were spread over avery small size range, as evident by the feed size distribution shown in Figure 6 (the feed particles in theNormandy trials were even more uniform). The unilormity in feed particle size results in a large amount offree space, which allow:s for swelling of the broken ore in the crushing chamber, thereby limiting theamount of interaction between particles. True "choke" feeding of the NCRC with ore having a widedistribution of particle sizes (especially in the smaller size range) is likely to generate much larger pressures 第 8 頁(yè) in the crushing zone. Since the NCRC is not designed to act as a "'high pressure grinding roll" a largernumber of oversize particles would pass between the rolls under these circumstances.Roll gapAs with a traditional roll crusher, the roll gap setting on the NCRC has a direct influence on the productsize distribution and throughput of the crusher. Figure 7 shows the resulting product size distributionobtained when the Aurora Gold ore (mill scats) was crushed at three different roll gaps. Plotting the PSOvalues taken from this graph against the roll gap yields the linear relationship shown in Figure 8. Asexplained previously, the actual roll gap on the NCRC will vary over one revolution. This variationaccounts for the difference between the specified gap setting and product Ps0 obtained from the crushingtrials. Figure 8 also shows the effect of roll gap on throughput of the crusher and gives an indication of thecrushing rates that can be obtained with the laboratory scale model NCRC. 第 9 頁(yè) Roll forceThe NCRC is designed to operate with minimal interaction between particles, such that comminution isprimarily achieved by fracture of particles directly between the rolls. As a consequence, the roll force onlyneeds to bc large enough to overcome the combined compressive strengths of the particles between the roll 第 10 頁(yè) surlaces. If the roll force is not large enough then the ore particles will separate the rolls allowing oversizedparticles to lall through. Increasing the roll force reduces the tendency of the rolls to separate and thereforeprovides better control over product size. However, once a limiting roll force has been reached (which isdependent on the size and type of material being crushed) any further increase in roll force adds nothing tothe performance of the roll crusher. This is demonstrated in Figure 9, which shows that for granite feed of25-3 Imm size, a roll force of approximately 16 to 18 kN is required to control the product size. Using alarger roll force has little effect on the product size, although there is a rapid increase in product P80 if theroll force is reduced bek>w this level.As mentioned previously, the feed size distribution has a significant effect on the pressure generated in thecrushing chamber. Ore that has a finer feed size distribution tends to "choke" the NCRC more, reducing theeffectiveness of the crusher. However, as long as the pressure generated in not excessive the NCRCmaintains a relatively constant operating gap irrespective of the feed size. The product size distributionwill, therefore, also bc independent of the feed size distribution. This is illustrated in Figure 10, whichshows the results of two crushing trials using identical equipment settings but with feed ore havingdifferent size distributions. In this example, the NCRC reduced the courser ore from an Fs0 of 34mm to aPs0 of 3.0mm (reduction ratio of 11:1), while the finer ore was reduced from an Fs0 of 18mm to a Pso of3.4mm (reduction ratio of 5:1). These results suggest that the advantages of using profiled rolls diminish asthe ratio of the feed size to roll size is reduced. In other words, to achieve higher reduction ratios the feedparticles must be large enough to take advantage of the improved nip angles generated in the NCRC. 第 11 頁(yè) Mill scatsSome grinding circuits employ a recycle or pebble crusher (such as a cone crusher) to process materialwhich builds up in a mill and which the mill finds hard to break (mill scats). The mill scats often containworn or broken grinding media, which can find its way into the recycle crusher. A tolerance to uncrushablematerial is therefore a desirable characteristic for a pebble crusher to have. The NCRC seems ideally suitedto such an application, since one of the rolls has the ability to yield allowing the uncrushable material topass through.The product size distributions shown in Figure 1 1 were obtained from the processing of mill scats in theNCRC. Identical equipment settings and feed size distributions were used for both results, however one ofthe trials was conducted using feed ore in which the grinding media had been removed. As expected, theNCRC was able to process the feed ore containing grinding media without incident. However, since oneroll was often moving in order to allow the grinding media to pass, a number of oversized particles wereable to fall through the gap without being broken. Consequently, the product size distribution for this feedore shows a shift towards the larger particle sizes, and the Ps0 value increases from 4ram to 4.7mm. In spiteof this, the NCRC was still able to achieve a reduction ratio of almost 4:1. 第 12 頁(yè) WearAlthough no specific tesls were conducted to determine the wear rates on the rolls of the NCRC, a numberof the crushing trials were recorded using a high-speed video camera in order to try and understand thecomminution mechanism. By observing particles being broken between the rolls it is possible to identifyportions of the rolls which are likely to suffer from high wear and to make some subjective conclusions asto the effect that this wear will have on the perlbrmance of the NCRC. Not surprisingly, the region thatshows up as being the prime candidate for high wcar is the transition between the flat and concave surfaces.What is surprising is that this edge does not play a significant role in generating the improved nip angles.The performance of the NCRC should not be adversely effccted by wear to this edge because it is actuallythe transition between the fiat and convex surfaces (on the opposing roll) that results in the reduced nipangles.The vide() also shows that tor part of each cycle particles are comminuted between the flat surfaces of therolls, in much the same way as they would be in a jaw crusher. This can be clearly seen on the sequence ofimages in Figure 12. The wear on the rolls during this part of the cycle is likely' to be minimal since there islittle or no relative motion between the particles and the surface of the rolls. 第 13 頁(yè) CONCLUSIONSThe results presented have demonstrated some of the factors effecting the comminution of particles in anon-cylindrical roll crusher. The high reduction ratios obtained from early single particle tests can still beachieved with continuous multi-particle feed. However, as with a traditional roll crusher, the NCRC issusceptible to choke feeding and must be starvation fed in order to operate effectively. The type of feedmaterial has little effect on the performance of the NCRC and, although not tested, it is anticipated that themoisture content of the feed ore will also not adversely affect the crusher's per[Brmance. Results from themill scat trials are particularly promising because they demonstrate that the NCRC is able to process orecontaining metal from worn grinding media. The above factors, in combination with the flaky nature of theproduct generated, indicate that the NCRC would make an excellent recycle or pebble crusher. It wouldalso be interesting to determine whether there is any difference in the ball mill energy required to grindproduct obtained from the NCRC compared that obtained from a cone crusher.