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1 改良鹽堿地利用煙氣脫硫副產(chǎn)品:生產(chǎn)力和環(huán)境質(zhì)量
1.1摘要
在這項(xiàng)研究中,煙氣脫硫( FGD )的副產(chǎn)品是用來減輕土壤鹽堿. 平均應(yīng)用率為土壤與低可交換鈉百分?jǐn)?shù)( ESP )協(xié)議,年年除塵器,高除塵器的20.9% , 30.6和59.3毫克房: 1 . 實(shí)驗(yàn)結(jié)果連續(xù)3年發(fā)現(xiàn)的出現(xiàn)率和產(chǎn)量的莊稼被1.1-7.6 倍和1.1-13.9倍以上的對(duì)照組,分別. 濃度的鉻,鉛,鎘,砷, 汞處理的土壤均遠(yuǎn)低于背景值規(guī)定的環(huán)境質(zhì)量標(biāo)準(zhǔn)的土( GB15618 - 1995年) . 其濃度的種子玉米和苜蓿種植處理土壤均遠(yuǎn)低于限量 受國家糧食標(biāo)準(zhǔn)中. 這項(xiàng)研究的結(jié)果表明,改良?jí)A性土壤利用脫硫副產(chǎn)品是充滿希望的.
1.2 簡介
濕法煙氣脫硫( FGD )是最主要的技術(shù)用在控制二氧化硫排放燃煤發(fā)電 植物. 主要副產(chǎn)品的過程是硫酸或混合固硫和CaSO4:EU (以下統(tǒng)稱為脫硫 byproducts ) . 隨著互聯(lián)網(wǎng)的迅速發(fā)展,對(duì)能源和電力行業(yè)在中國 裝機(jī)容量電廠煙氣脫硫裝置,因此這筆錢的煙氣脫硫副產(chǎn)品, 可望迅速增加. 到2005年底, 裝機(jī)我國發(fā)電廠脫硫裝置約為53兆瓦, 而每年生產(chǎn)的脫硫副產(chǎn)品約650萬噸. 據(jù)國家發(fā)展計(jì)劃中, 裝機(jī)容量電廠煙氣脫硫裝置將200 gw 2010年 年產(chǎn)脫硫副產(chǎn)品40萬噸; 到2020年,這些數(shù)字將530千兆瓦, 90萬噸. 由于脫硫副產(chǎn)品含有大量水分和灰分 他們只能被用作建筑石膏經(jīng)過凈化和脫水; 6684900經(jīng)濟(jì)處境比天然石膏產(chǎn)于中國. 如果脫硫副產(chǎn)品都可以直接處置而不采取任何利用或治療, 遼闊的土地需. 這種方式將浪費(fèi)寶貴的土地資源,是一個(gè)潛在威脅的二次污染 環(huán)境. 著 還有大面積的鹽堿地china.these在土壤不適宜種植農(nóng)作物,一些這樣的土壤 不支持任何植物的生長情況. 這些貧瘠的土地嚴(yán)重限制了農(nóng)業(yè)生產(chǎn)的發(fā)展產(chǎn)生負(fù)面影響,對(duì)ecosystem.according提供的統(tǒng)計(jì) 由國土資源部和資源在中國 共有346000平方公里( 3460萬公頃)堿性土壤,在西北,華北,東北, 而我國沿海地區(qū); 這些領(lǐng)域中, 土壤與重型交換性鈉百分?jǐn)?shù)( ESP )協(xié)議彌補(bǔ)約92000平方公里. 改良?jí)A性土壤對(duì)一個(gè)如此龐大的地區(qū)之一,面臨的最大挑戰(zhàn)之一,中國農(nóng)業(yè). 石膏已確知是一種改良劑鹽堿地超過100年; 不過, 它已很少使用,因?yàn)槌杀靖?參與開采,交通 粉碎天然石膏. 雖然主要組成部分,脫硫副產(chǎn)品為硫酸鈣,它們還含有約10%的堿性物質(zhì); 不過, 這是作為不確定是否脫硫副產(chǎn)品與PH值7.7-10.03 (徐et al . ,2005 )都適合使用 在改良鹽堿地. 事實(shí)上, 脫硫副產(chǎn)品已被用來作為一種改性的酸性土壤,在美國和其他國家(陳 et al . 2001年; 趙金亮. , 2004 ) . 松本教授,日本東京大學(xué)首先提出改良?jí)A性土壤利用脫硫副產(chǎn)品(馬塔莫羅斯 1998 ) . 改良鹽堿地利用脫硫副產(chǎn)品會(huì)利用這幾百萬噸的脫硫副產(chǎn)品, 從而提高應(yīng)用的煙氣脫硫技術(shù),并開發(fā)了控制污染的產(chǎn)業(yè). 此外, 在很大的程度上荒山鹽堿土壤改良的脫硫副產(chǎn)品就會(huì)適合農(nóng)作物生長的脈絡(luò) 農(nóng)作物; 這將大有益處以農(nóng)業(yè)發(fā)展和改善當(dāng)?shù)氐纳鷳B(tài).
1.3材料和方法
進(jìn)行田間試驗(yàn),對(duì)土壤鹽堿的土默川平原,呼和浩特,內(nèi)蒙古. 有2個(gè)實(shí)驗(yàn)田. 為一號(hào)實(shí)驗(yàn)田,總面積約2.67公頃; 土壤ESP則由6.1至78.4% ; 而土壤酸堿度8.5到9.77 . 在第2實(shí)驗(yàn)田,總面積6.67公頃; 土壤ESP從1940年至1950年左右; 而土壤酸堿度9.4-9.5.the濃度的主要因素,脫硫副產(chǎn)品分別用ICP-AES法, 雖然濃度的某些重金屬(鉛,鎘,鉻,銅,鎳,和SE ) ,確定用ICP-MS , 和砷和汞測(cè)定的ICP-AES與隨后的檢查用原子熒光光譜(AFS) . 化學(xué)組成的脫硫副產(chǎn)品見表1 . 一號(hào)實(shí)驗(yàn)田共分為3種類型根據(jù)土壤esp : 即低ESP場(土除塵器6.1e20 % ) ,中esp場(土esp 20-30% ) 高ESP場(土除塵器30-78.4 % ) . 平均應(yīng)用率為不同類型的刊載于表2 . 平均應(yīng)用率為第2實(shí)驗(yàn)場,分別為33毫克房1 . 控制領(lǐng)域也規(guī)定每年的3種一號(hào)實(shí)驗(yàn)田和二號(hào)實(shí)驗(yàn) 田. 該療法的實(shí)驗(yàn)和控制領(lǐng)域都是一樣,除適用fgd byproducts.for一號(hào) 實(shí)驗(yàn)田, 脫硫副產(chǎn)品被補(bǔ)充到土壤中,在一個(gè)單一的應(yīng)用在2001年春季,充分混合 與地面( 0-20厘米)的土壤. 2001年,被放置在低esp領(lǐng)域,飼用玉米種植中ESP 田, 而高ESP田飼料玉米種植在各種領(lǐng)域, 2002年 食品和玉米種植各類技術(shù)領(lǐng)域于2003年完成. 2號(hào)實(shí)驗(yàn)田, 脫硫副產(chǎn)品被補(bǔ)充到土壤中,在一個(gè)單一的應(yīng)用2004年7月,并充分混合著 表面( 0-20 cm )土壤. 苜蓿種植在同一年. 外地治療的兩個(gè)領(lǐng)域,包括施肥,除草, 灌溉根據(jù)當(dāng)?shù)氐霓r(nóng)業(yè)耕作于2003年10月 土壤樣品和玉米種子中抽取的1號(hào)實(shí)驗(yàn)田和控制領(lǐng)域中 土壤高esps確定重金屬濃度. 2005年9月,土壤樣品和苜蓿共收集到二號(hào)實(shí)驗(yàn)田. 土壤樣品 總鉛和總鎘測(cè)定的石墨爐原子吸收光譜按照國家標(biāo)準(zhǔn),土壤質(zhì)量 gb/t17141-1997 ,總鎘的測(cè)定火焰原子吸收光譜按照gb/t17138-1997 ,總汞濃度測(cè)定戰(zhàn)地, 總所采用銀鹽分光. 植物樣本中,鉛乃根據(jù)gb/t5009.12-2003 (測(cè)定食品中的鉛) 唯要按gb/t5009.15-2003 (測(cè)定食品中鎘) 如按gb/t5009.11-2003 (測(cè)定總砷及無機(jī)砷的食品) , 鉻要按gb/t5009.123-2003 (測(cè)定鉻的食物) ,汞的含量是采用AFS
1.4結(jié)果和討論
2001年 的出苗率和產(chǎn)量mignonette分別為1.2倍和4.2倍以上的對(duì)照組,分別 而出苗率和產(chǎn)量的飼用玉米的5.6倍和7.6倍以上的對(duì)照 (見表3 ) . 2002年 的出苗率和產(chǎn)量的飼用玉米的1.1-7.6倍和1.1e6.8倍以上的對(duì)照組, 分別 而出苗率和產(chǎn)量鮮食玉米的1.1-3.7倍和1.6-13.9倍以上的對(duì)照組, 分別取決于土壤esp . 出現(xiàn)比率與收益的作物,土壤變ESP列圖. 1-4
在審圖1和2 很明顯,出現(xiàn)比玉米實(shí)驗(yàn)田均高于控制領(lǐng)域 尤其土壤具有較高esp . 出現(xiàn)比率雞眼在土壤高ESP為70% , 2002年 這是93.3% ,在2003年. 顯然是無花果. 3 ,生物產(chǎn)量的飼用玉米的待遇高土壤ESP達(dá)到51毫克房 1 ,大大高于7.5毫克房1在控制領(lǐng)域, 也高于32毫克房1在控制領(lǐng)域中,與土壤esp . 這也是從無花果. 4 ,制種產(chǎn)量的玉米食品的治療領(lǐng)域與土壤高esp是8618公斤房 1 , 8000公斤房1比在控制. 這表明,煙氣脫硫副產(chǎn)品是更為有效的農(nóng)田土壤高esp并產(chǎn)生了顯著增加 在作物產(chǎn)量. 相比專業(yè)領(lǐng)域與低土esp ,但作物產(chǎn)量領(lǐng)域內(nèi)高esp仍較低. 這也是從無花果樹. 1e4 ,結(jié)果在2003年高于2002年. 2003年 出現(xiàn)率和作物產(chǎn)量分別為93.3和8618公斤, 1公頃高于esp土壤. 上述結(jié)果表明不毛之地已成功地轉(zhuǎn)變成培養(yǎng)土. 2005年,出苗率苜蓿是30e50 %的實(shí)驗(yàn)田, 和產(chǎn)量分別1333e4335公斤1公頃,平均2079公斤, 1公頃. 作為比較, 的出苗率和產(chǎn)量幾乎為零的控制fields.the施用脫硫副產(chǎn)物 重金屬濃度的作物和土壤進(jìn)行了評(píng)估. 初步評(píng)估涉及3個(gè)階段. 第一期工程涉及的檢測(cè)重金屬濃度脫硫副產(chǎn)品(見表1 ) . 表4顯示的元素濃度規(guī)定控制標(biāo)準(zhǔn)的污染物,在粉煤灰用于農(nóng)業(yè)(GB8173 - 1987 ) 環(huán)境質(zhì)量標(biāo)準(zhǔn)的土壤( gb15618 - 1995年) . 顯然,從388.4重金屬濃度在 煙氣脫硫副產(chǎn)品,都遠(yuǎn)遠(yuǎn)低于國家標(biāo)準(zhǔn)限制中國: 大部分都低于背景值的土壤,第二階段是分析重金屬濃度 處理和對(duì)照土壤(表5 ) . 濃度的鉻,鉛,以及在處理與土壤esp年年增加,相對(duì)地控制土壤. 濃度鎘汞在土壤中ESP與各個(gè)分析元素在土壤高esp 下降,相對(duì)的控制濃度的鉛鎘 汞在土壤中的第2號(hào)實(shí)驗(yàn)田略有增加相對(duì)地控制濃度全部 重金屬分析的試驗(yàn)性治療,都遠(yuǎn)遠(yuǎn)低于土壤背景值受環(huán)境質(zhì)量標(biāo)準(zhǔn) 土壤( GB15618 - 1995年) .
最后階段,涉及的重金屬含量分析玉米種子和苜蓿(見表6 ) . 沒有改變被發(fā)現(xiàn)的重金屬濃度的種子種玉米和苜蓿種植在 土壤處理相比增長控制土壤. 結(jié)果,這項(xiàng)初步研究表明,應(yīng)用脫硫副產(chǎn)品不會(huì)污染土壤或作物 生長于土壤中,但更詳盡的研究,仍有待進(jìn)行.
1.5結(jié)論
改良鹽堿地利用脫硫副產(chǎn)品貨源來自發(fā)電廠變化不毛之地變成耕地土壤 帶來巨大的社會(huì)和經(jīng)濟(jì)效益. 實(shí)驗(yàn)結(jié)果連續(xù)3年應(yīng)用后煙氣脫硫副產(chǎn)品在2001年發(fā)現(xiàn)的涌現(xiàn) 比值與植物作物產(chǎn)量分別1.1-7.6 倍和1.1-13.9倍以上的對(duì)照組,分別 依靠土壤ESP . 重金屬濃度在處理后的土壤和作物生長的土壤遠(yuǎn)遠(yuǎn)低于土壤 背景值和限量的規(guī)定由國家食品標(biāo)準(zhǔn). 這項(xiàng)研究的結(jié)果表明,改良?jí)A性土壤利用脫硫副產(chǎn)品是充滿希望的. 鳴謝這項(xiàng)研究是在財(cái)力上支持了國家科技部和教育部.
2 宏觀對(duì)廢氣脫硫副產(chǎn)物的微觀研究為酸礦排水設(shè)備緩和
2.1簡介
對(duì)廢氣脫硫(FGD) 系統(tǒng)的用途減少二氧化硫放射導(dǎo)致很大數(shù)量的副產(chǎn)物的世代。這些和其它副產(chǎn)物被儲(chǔ)備在時(shí)間, 堿性材料有高中立化潛力是需要的緩和酸礦排水設(shè)備(AMD) 。FGD 副產(chǎn)物是高度堿性材料組成主要由無反應(yīng)的吸著劑(石灰或石灰石和硫化和加州硫化物) 。大約20 百萬噸FGD 材料由電力公共事業(yè)引起了被裝備以濕石灰石灰石FGD 系統(tǒng)根據(jù)lastest 演算(l993) 。少于5% 這材料被投入了對(duì)有利用途為農(nóng)業(yè)土壤校正和為墻板和水泥的生產(chǎn)。
四個(gè)USGS 項(xiàng)目審查FGD 副產(chǎn)物用途表達(dá)這些關(guān)心。這些項(xiàng)目介入1) 計(jì)算廢氣脫硫(FGD) 副產(chǎn)物世代和他們的地理位置的容量關(guān)于AMD, 2) 確定副產(chǎn)物化學(xué)并且礦物學(xué), 3) 大氣燃燒副產(chǎn)物評(píng)估的水文學(xué)和地球化學(xué)當(dāng)土壤校正在俄亥俄, 和4) 分析石膏的微生物退化在缺氧石灰石里排泄在西維吉尼亞。
2.2 美國FGD 數(shù)據(jù)庫
礦物信息(以前美國局辦公室的工業(yè)礦物分支礦) 在USGS 開發(fā)了可能被使用提供信息在FGD 副產(chǎn)物和潛在市場可及性和接近度, 譬如墻板植物、波特蘭水泥工業(yè), 和AMD 問題范圍的一個(gè)地理信息系統(tǒng)(GIS) 。以這信息, 我們能第一次估計(jì)FGD 副產(chǎn)物市場經(jīng)濟(jì)潛力在全國范圍內(nèi)。
電力公共事業(yè)的發(fā)行被裝備以FGD 單位普遍(圖1) 。FGD 副產(chǎn)物生產(chǎn)和儲(chǔ)積對(duì)年1998 年由能量信息管理(圖2) 展望了。以當(dāng)前的生產(chǎn)率, 盡量200 百萬公噸FGD 材料將引起和將被存放主要在垃圾填埋里至2000年。這是高度堿性材料的極大的容量。一個(gè)重要宗旨將, 因此, 描繪FGD 副產(chǎn)物化學(xué)和礦物學(xué)辨認(rèn)有利和有害組分。
2.3 FGD 飼料石灰石和副產(chǎn)物的描述特性
USGS 、肯塔基地質(zhì)調(diào)查, 和肯塔基公共事業(yè)創(chuàng)始項(xiàng)目收集信息關(guān)于飼料煤炭、飼料石灰石、飛煙、底下灰, 和FGD 副產(chǎn)物化學(xué)和礦物學(xué)在肯塔基能源廠。每個(gè)的樣品這些材料被收集在月度間隔時(shí)間。分析廣品種在每個(gè)包括集中多達(dá)50 個(gè)元素; 礦物學(xué)(X-射線衍射, 光學(xué)巖相學(xué)); 發(fā)生(掃描電子顯微鏡術(shù), microprobe 分析方式, 有選擇性浸出); 有機(jī)地球化學(xué); 放射性核素分析; 浸出的做法的毒性描述特性(TCLP); 并且專欄浸出。
結(jié)果從這個(gè)數(shù)據(jù)庫將使可利用和被預(yù)計(jì)提供洞察入化學(xué)的飼料石灰石和煤炭的影響和礦物學(xué)在FGD 爛泥化學(xué)。一個(gè)重要宗旨將使用數(shù)據(jù)確定各種各樣的副產(chǎn)物組分的相對(duì)反應(yīng)性在地表和地面水里。
2.4 FGD 副產(chǎn)物運(yùn)用的地表和地面水描述特性在示范站點(diǎn)在TUSCARAWAS 縣, 俄亥俄
FGD 副產(chǎn)物是應(yīng)用的在一個(gè)被摒棄的表面煤礦在Tuscarawas 縣, 俄亥俄中立化AMD, 得知變化在水化學(xué)上, 和增加土壤強(qiáng)堿性對(duì)援助在反蔬菜。這研究是共同努力在USGS 水源分部(俄亥俄區(qū)) 并且俄亥俄州立大學(xué)之間。
干燥FGD 副產(chǎn)物向表面被應(yīng)用了在晚1994 在45 英畝農(nóng)莊站點(diǎn)的開墾期間。前開墾硫水放電從站點(diǎn)是酸性的(酸堿度2.9 到5.5) 并且侵蝕是嚴(yán)厲的由于缺乏植被。FGD 材料向六1 英畝測(cè)試意義重大被應(yīng)用了在4 腳厚實(shí)的酸性礦掠奪物基地。3 種開墾治療三件復(fù)制品向各掠奪物表面, 或者被應(yīng)用了作為(1) 8 in. 標(biāo)準(zhǔn)開墾實(shí)踐表土被修正與ag 石灰; (2) 8 in. 表土修正了與125 tons/acre 干燥FGD 副產(chǎn)物; 或(3) 8 in. 表土修正了以干燥FGD 副產(chǎn)物混合和圍場浪費(fèi)天然肥料。
另外, FGD 材料是應(yīng)用的以125 tons/acre 的率對(duì)被整頓的minespoil 在圍攏測(cè)試劇情的緩沖帶。
FGD 材料物理, 礦物學(xué), 和工程學(xué)物產(chǎn)被用于在Fleming 站點(diǎn)廣泛地被調(diào)查了[ 3,4,5 ] 。干燥FGD 副產(chǎn)物被使用在這項(xiàng)研究由一個(gè)大氣硫化床鍋爐導(dǎo)致了經(jīng)營在通用汽車公司植物在Pontiac, Mich 。鍋爐用途煤炭和石灰石生產(chǎn)了在俄亥俄。組成部分有存在主要或次要飲用水標(biāo)準(zhǔn)和因此潛力有害影響在水質(zhì)如果浸出以充足的數(shù)量從FGD 副產(chǎn)物包括和(47 ppm), Cr (75 ppm), Ni (55 ppm), 鉛(36 ppm), Se (11 ppm), 和SO4 (18 到21 重量百分之作為SO4) 。漿糊酸堿度FGD 副產(chǎn)物范圍從10 到12, 并且CaCO3 相等范圍從37.7 到39.5 噸CaCO3/100 噸副產(chǎn)物。
農(nóng)莊站點(diǎn)的水文地質(zhì)學(xué)和地球化學(xué)由巖石挖出果核調(diào)查了和完全巖石分析、35 土壤吸測(cè)試劑和20 口監(jiān)測(cè)的井, 和表面和鉆孔地球物理。測(cè)試劑被安裝了在1.5-4.5 ft 深度, 但是井被篩選了在大約30-100 ft 深度。水平面、具體導(dǎo)率, 和溫度每小時(shí)被測(cè)量了在7 口自動(dòng)化的監(jiān)測(cè)的井從1995 年6月。由于高硫集中在淺地下水里由AMD 影響和在FGD處理上, 被溶化的硫的同位素構(gòu)成被調(diào)查作為FGD 副產(chǎn)物處理上一個(gè)可能的追蹤者。
原始結(jié)果表明, 水面的構(gòu)成和淺水孔由FGD 副產(chǎn)物處理影響了。水孔從測(cè)試劑收集了在應(yīng)用范圍有PH 值大于6.5, Fe 含量少于1.0 mg/L 硫集中大約5,000 到10,000 mg/L, 和槽牙Mg:Ca 比率大于5, 但是毛孔水抽樣從測(cè)試劑被安裝在應(yīng)用范圍之外有是因素5 到10 低比那些在樣品從測(cè)試劑在應(yīng)用范圍里面的更低的PH 值(4.4-5.7) 并且硫和被溶化的固體含量。滲入不飽和的礦井的這數(shù)據(jù)與假說是一致的, 堿性測(cè)試劑中立化酸度由硫鐵礦的氧化作用導(dǎo)致。結(jié)果是近中立PH 值和低被溶化的鋼和鋁含量。高硫集中主要反射浸出FGD 材料的石膏組分。
相反, 地下水在農(nóng)莊站點(diǎn)之下典型地有5 到6, 幾百mg/L 的被溶化的Fe 含量, 硫集中的PH 值幾百對(duì)幾一千個(gè)mg/L, 和Mg:Ca 槽牙比率相反, 地下水在農(nóng)莊站點(diǎn)之下典型地有PH值的5到6, 被溶化的Fe含量幾百鎂L, 硫化集中幾百對(duì)幾一千毫克L, 并且鎂:加州槽牙比率<1.0。 這數(shù)據(jù)建議處理從FGD副產(chǎn)物未到達(dá)其中任一口本地監(jiān)視井。 然而, 因?yàn)槎鄶?shù)降雨雪通過地面徑流過程線留下站點(diǎn), 再充電對(duì)淺蓄水層是慢的(大約3到5寸年)。 因而FGD 處理的作用在地水在農(nóng)莊站點(diǎn)之下未被查出,并且?guī)啄瓯O(jiān)視也許是需要的。 地水樣品將通過1998年年年收集估計(jì)長期變動(dòng)進(jìn)入水質(zhì)。
高的硫在水孔, 和最終在地下水, 被期望被給FGD 副產(chǎn)物的化工本質(zhì)。下個(gè)實(shí)驗(yàn)被設(shè)計(jì)學(xué)會(huì)更多關(guān)于石膏的溶解和被溶化的硫命運(yùn)在環(huán)境里。
2.5 微生物互作用與石膏在RIDENOUR 舷梯缺氧石灰石流失站點(diǎn), MORGANTOWN, 西維吉尼亞
在AMD 環(huán)境里已經(jīng)有硫化物過剩, 它是重要學(xué)會(huì)怎么FGD 礦物石膏將行動(dòng)在領(lǐng)域情況下。石膏的溶解被分析了參加一系列缺氧石灰石流失(ALD) 在Morgantown, WV這里 附近。修造在酸性排水設(shè)備流出, ALD 的是溝槽用石灰石石渣被填裝增加強(qiáng)堿性和然后被蓋保持他們?nèi)毖跻员憬饘俦A粼诮獯? 不涂上石灰石石渣。許多ALD 的無法在月內(nèi)作為石渣成為塞住與鋼和氫氧化鋁。
ALD 的被使用在這個(gè)實(shí)驗(yàn)被修造了在一個(gè)被摒棄的煤礦位于Ridenour 站點(diǎn)Morgantown, WV 8.5 公里東北部。1992 年區(qū)域被索還了由USDA USDA-自然資源 保護(hù)服務(wù)(以前SCS) 。Ridenour 農(nóng)村被摒棄的礦節(jié)目(舷梯) 站點(diǎn)設(shè)計(jì)包括3 缺氧石灰石流失與其它開墾工作[ 7 一起] 。在建筑期間, 監(jiān)測(cè)井被安裝了在ALD 的, 并且導(dǎo)線籠子用石灰石石渣被填裝是暫停的洞下的監(jiān)測(cè)進(jìn)步變化在石渣表面上。在6 個(gè)月內(nèi), 石灰石在一口井("黑流失" 好) 依照由能量分散性分光學(xué)確定變得上漆與包含F(xiàn)e 但的黑沉淀物缺乏Mn 和S 。
實(shí)驗(yàn)性設(shè)計(jì)包括添加的透明石膏水晶對(duì)顯微鏡幻燈片。玻璃控制幻燈片, 與石膏上漆的幻燈片一起, 附有了導(dǎo)線籠子和暫停深井在監(jiān)視井調(diào)查微生物和化工互作用與石膏?;脽羝涣粝略诒O(jiān)視井6 個(gè)星期在1996 年的春天, 和然后被收集了為微生物分析。
此時(shí), 化工和微生物分析只被承擔(dān)了在"黑流失" 好。但是表面酸堿度是酸的當(dāng)ALD 被修造了,洞下的酸堿度現(xiàn)在是6.3 。在6 個(gè)星期,大腸桿菌細(xì)菌附有兩張幻燈片。石膏幻燈片依然是透明; 無色和棕色短的標(biāo)尺稀稀落落地被分布了在補(bǔ)丁。玻璃控制幻燈片由短和長的無色的標(biāo)尺涂上了。
這些結(jié)果表示, 石膏整體上沒有溶化在表層下情況下在"黑流失" 現(xiàn)場。石膏水晶看上去作為一種惰性物質(zhì)至少為短期在這個(gè)最初的實(shí)驗(yàn); 但是, 水是已經(jīng)滲透談到石膏(表1), 建議石膏最終將溶化。
2.6結(jié)論
盡量200 百萬公噸FGD 副產(chǎn)物將至2000年引起。發(fā)現(xiàn)有利用途為這高度堿性材料的極大的容量是駕駛的因素在我們的研究。詳細(xì)的化學(xué)和礦物學(xué)被分析在FGD 飼料石灰石和副產(chǎn)物從一個(gè)能源廠在肯塔基。地球化學(xué)和水文學(xué)研究在一個(gè)站點(diǎn)在俄亥俄使用FGD 副產(chǎn)物作為一個(gè)農(nóng)業(yè)校正表示, 酸度和鋼含量被減少了, 但是硫增加了在水孔里。石膏的溶解, FGD 副產(chǎn)物主要硫組分的微生物學(xué)的研究, 表示, 微生物附件是顯然的在20 天之內(nèi)并且, 石膏看上去作為一種惰性物質(zhì)至少在短期??偣? 初階結(jié)果從這數(shù)據(jù)和實(shí)驗(yàn)表示, FGD 副產(chǎn)物極大的容量和強(qiáng)堿性有諾言至于使用在AMD 緩和。
10
xxx大學(xué)
本科畢業(yè)設(shè)計(jì)(論文)
150MW燃煤電廠煙氣除塵脫硫工程設(shè)計(jì)
學(xué) 院 環(huán)境科學(xué)與工程學(xué)院
專 業(yè) 環(huán)境工程
年級(jí)班別
學(xué) 號(hào)
學(xué)生姓名
指導(dǎo)教師
20xx 年 06 月
任務(wù)書
題目名稱
150MW燃煤電廠煙氣除塵脫硫工程設(shè)計(jì)
學(xué)生學(xué)院
環(huán)境科學(xué)與工程學(xué)院
專業(yè)班級(jí)
姓 名
學(xué) 號(hào)
一、畢業(yè)設(shè)計(jì)(論文)的內(nèi)容
燃煤電廠煙氣除塵脫硫工程設(shè)計(jì),包括各種除塵脫硫的工藝原理、各種除塵脫硫的工藝方法比較、主體設(shè)備選型和非標(biāo)準(zhǔn)設(shè)備設(shè)計(jì),管道輸送系統(tǒng)設(shè)計(jì)及工程投資概算等。
二、畢業(yè)設(shè)計(jì)(論文)的要求與數(shù)據(jù)
廢氣處理量:畢業(yè)實(shí)習(xí)收集,或者“按產(chǎn)排污系數(shù)手冊(cè)”;
廢氣成分:畢業(yè)實(shí)習(xí)收集,或者“按產(chǎn)排污系數(shù)手冊(cè)”;
畢業(yè)實(shí)習(xí)10天以上;實(shí)習(xí)報(bào)告(含資料調(diào)研報(bào)告)10000字以上;
??? 畢業(yè)設(shè)計(jì)說明書30000字以上;
繪制工程設(shè)計(jì)圖紙8張(A4)以上。
三、畢業(yè)設(shè)計(jì)(論文)應(yīng)完成的工作
查閱和翻譯文獻(xiàn)資料;
參與畢業(yè)實(shí)習(xí)并編寫實(shí)習(xí)報(bào)告;
編寫畢業(yè)設(shè)計(jì)說明書;
進(jìn)行工程概算和運(yùn)行可行性分析;
繪制工程設(shè)計(jì)圖紙。
序號(hào)
設(shè)計(jì)(論文)各階段內(nèi)容
起止日期
1
參與畢業(yè)實(shí)習(xí)
3月15日~4月12日
2
編寫實(shí)習(xí)報(bào)告、查閱和翻譯文獻(xiàn)資料
4月13~4月25日
3
研究設(shè)計(jì)方案,進(jìn)行設(shè)計(jì)的有關(guān)計(jì)算
4月26日~5月10日
4
編寫畢業(yè)設(shè)計(jì)說明書
5月11日~5月25日
5
進(jìn)行工程概算和運(yùn)行可行性分析
5月26日~5月29日
6
繪制工程設(shè)計(jì)圖紙
5月30日~6月8日
7
答辯準(zhǔn)備及答辯
6月9日~6月12日
四、畢業(yè)設(shè)計(jì)(論文)進(jìn)程安排
五、應(yīng)收集的資料及主要參考文獻(xiàn)
1. 王志魁主編 . 化工原理 .第二版.北京:化學(xué)工業(yè)出版社,1998.10
2. 赫吉明 馬廣大主編 . 大氣污染控制工程. 第二版.北京:高等教育出版社,2002
3. 賀匡國主編.化工容器及設(shè)備簡明設(shè)計(jì)手冊(cè).化學(xué)工業(yè)出版社,1989
4. 黃學(xué)敏.張承中主編. 大氣污染控制工程實(shí)踐教程.北京:化學(xué)工業(yè)出版社. 2003.9
5. 立本英機(jī).安部郁夫(日)主編.高尚愚譯編. 活性炭的應(yīng)用技術(shù)ü其維持管理及存在問題.南京:東南大學(xué)出版社,2002.7
6. 林肇信主編.大氣污染控制工程.高等教育出版社.1991.5
7. 全燮.楊鳳林主編. 環(huán)境工程計(jì)算手冊(cè).中國石化出版社.2003.6
8. 吳忠標(biāo)主編 . 實(shí)用環(huán)境工程手冊(cè)ü大氣污染控制工程 化學(xué)工業(yè)出版社. 2001.9
9. 姜安璽主編. 空氣污染控制 .北京:化學(xué)工業(yè)出版社. 2003
10. 朗曉珍. 楊毅宏主編. 冶金環(huán)境保護(hù)及三廢治理技術(shù). 東北大學(xué)出版社. 2002
11. 童志權(quán)等主編. 工業(yè)廢氣污染控制與利用. 北京:化學(xué)工業(yè)出版社,1988
12. 王紹文.張殿印.徐世勤.董保澍主編. 環(huán)保設(shè)備材料手冊(cè).冶金工業(yè)出版社 2000.9
13. 朱世勇,《環(huán)境與工業(yè)氣體凈化技術(shù)》,化學(xué)工業(yè)出版社,2001
14. 李光超,《大氣污染控制技術(shù)》,化學(xué)工業(yè)出版社,2002
15. L.Ekman.LIFAC-經(jīng)濟(jì)有效的脫硫方法.芬蘭:Fortum Engineering Ltd.
16. 唐敬麟,張祿虎編. 除塵裝置系統(tǒng)及設(shè)備設(shè)計(jì)選用手冊(cè)化學(xué)工業(yè)出版社.2004
17. 《給水排水設(shè)計(jì)手冊(cè) (第11卷)》,中國建筑工業(yè)出版社,1986.
18. 趙毅,李守信,《有害氣體控制工程》,化學(xué)工業(yè)出版社,2001.
19. 陳常貴、曾敏靜、劉國雄等編,《化工原理》,天津科學(xué)技術(shù)出版社,2002
20. Licht,W《Air Pollution Control Engineering》.Publisher,New York,NY(US);Marcel Dekker,Inc.System Entry Date:2001 May 13.
21. Dry Removal of Gaseous Pollutants from Flue Gases with the GFB(FGD by CFB).Lurgi Report,Germany,1990..
22. 劉天齊主編,三廢處理工程技術(shù)手冊(cè):廢氣卷,北京:化學(xué)工業(yè)出版社 1999.5
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1. Amelioration of alkali soil using flue gas desulfurization byproducts: Productivity and environmental quality
1.1 Abstract:
In this study, flue gas desulfurization (FGD) byproducts are used to ameliorate alkali soil. The average application rates for soils with low exchangeable sodium percentage (ESP), mid ESP, and high ESP are 20.9, 30.6, and 59.3 Mg ha 1, respectively. The experimental results obtained for 3 consecutive years reveal that the emergence ratios and yields of the crops were 1.1-7.6 times and 1.1-13.9 times those of the untreated control, respectively. The concentrations of Cr, Pb, Cd, As, and Hg in the treated soils are far below the background values stipulated by the Environmental Quality Standard for Soils (GB15618-1995). Their concentrations in the seeds of corn and alfalfa grown in the treated soils are far below the tolerance limits regulated by National Food Standards of China. The results of this research demonstrate that the amelioration of alkali soils using FGD byproducts is promising.
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1.2 Introduction
Wet flue gas desulfurization (FGD) is the dominant technology used in the control of SO2 emissions from coal-fired power plants. The major byproduct of the process is CaSO4 or a mixture of CaSO3 and CaSO4 (herein referred to as FGD byproducts). With the rapid development of the energy and power industries in China, the installed capacity of power plants with FGD devices, and therefore the amount of FGD byproduct, is expected to increase rapidly. By the end of 2005, the installed capacity of power plants in China with FGD devices was about 53 GW, and the annual production of FGD byproducts was about 6.5 million tons. According to the National Development Program of China, the installed capacity of power plants with FGD devices will be 200 GW by 2010, with an annual production of FGD byproducts of 40 million tons; by 2020,these figures will be 530 GW and 90 million tons. As FGD byproducts contain large amounts of moisture and ash, they can only be used as building gypsum after purification and dehydration; this represents an economic disadvantage compared with natural gypsum produced in China. If the FGD byproducts were to be directly disposed of without any utilization or treatment, a vast area of land would be required. Such an approach would be a waste of valuable land resources and represent a potential threat of secondary pollution to the environment. Significantly, there are large areas of alkali soil in China.These soils are unsuitable for growing agricultural crops,and some such soils are unable to support any plant growth whatsoever. These barren lands severely limit agriculture production in China and have a negative impact on the ecosystem.According to statistics provided by the Ministry of Land and Resource in China, there are 346000 km2 (34.6 million ha) of alkali soils in the northwest, north, northeast, and coastal areas of China; of these areas, soils with heavy exchangeable sodium percentage (ESP) make up about 92 000 km2. The amelioration of alkali soils over such an enormous area is one of the greatest challenges facing Chinese agriculture. Gypsum has been known to be an amelioration agent for alkali soil for more than 100 years; however, it has been used only rarely because of the high cost involved in the exploitation, transportation, and crushing of natural gypsum. Although the main component of FGD byproducts is CaSO4, they also contain about 10% alkali material; however, it is uncertain as to whether FGD byproducts with a pH of 7.7-10.03 (Xu et al.,2005) are suitable for use in the amelioration of alkali soil. In fact, FGD byproducts have been used as a type of modifier for acid soil in the US and other countries (Chen et al., 2001; Li et al., 2004). Professor Matsumoto of Tokyo University firstly proposed the amelioration of alkali soils using FGD byproducts(Matsumoto, 1998).The amelioration of alkali soil using FGD byproducts would make use of tens of millions of tons of FGD byproducts, thereby boosting the application of FGD technology and the development of the pollution-control industry. In addition, the huge extent of barren alkali soil ameliorated by the FGD byproducts would then be suitable for growing agricultural crops; this would be of significant bene?t to both agricultural development and improvement to local ecosystems.
1.3 Materials and methods
Field studies were conducted on alkali soil upon the Tumochuan Plain, Huhhot, Inner Mongolia. There are 2 experimental fields. For the No. 1 experimental fields, the total area is about 2.67 ha; soil ESP ranges from 6.1 to 78.4%; and the soil pH is 8.5e9.77. For the No. 2 experimental fields, the total area is 6.67 ha; soil ESP ranges from 40 to 50%; and the soil pH is 9.4e9.5.The concentrations of the main elements in the FGD byproducts were determined using ICP-AES, while the concentrations of certain heavy metals(Pb, Cd, Cr, Cu, Ni, and Se) were determined using ICP-MS, and As and Hg were determined using ICP-AES with a subsequent check using atomic fluorescence spectrophotometry (AFS). The chemical composition of the FGD byproducts is shown in Table 1.
The No. 1 experimental fields were divided into 3 types according to soil ESP: i.e. low ESP fields (soil ESP of 6.1e20%), mid ESP fields (soil ESP of 20-30%), and high ESP fields (soil ESP of 30e78.4%). The average application rates for the different types of ?elds are given in Table 2. The average application rates for No. 2 experimental fields were 33 Mg ha 1. Control fields were also set for each of the three types of No. 1 experimental fields and No. 2 experimental ?elds. The treatments for the experimental and control fields were the same except for the application of FGD byproducts.For No. 1 experimental ?elds, the FGD byproducts were added to the soil in a single application during the spring of 2001 and fully mixed with the surface (0-20 cm) soil. In 2001, mignonette was planted in the low ESP fields,forage corn was planted in the mid ESP ?elds, and the high ESP fields were left unplanted. Forage corn was planted in all types of fields in 2002, and
food corn was planted in all types of fields in 2003. For No. 2 experimental fields, the FGD byproducts were added to the soil in a single application in July 2004 and fully mixed with the surface (0e20 cm) soil. Alfalfa was planted in the same year. The field treatments for both fields included fertilizing, weeding, and irrigation in accordance with local agricultural practices In October 2003, samples of soil and corn seed were collected from the No. 1 experimental fields and control fields with mid and high soil ESPs to determine the concentrations of heavy metals. In September 2005, samples of soil and alfalfa were collected from No. 2 experimental fields. For soil samples, total Pb and total Cd were determined using graphite furnace atomic absorption spectrophotometry according to National Standards for Soil Quality GB/T17141-1997, total Cd was determined using flame atomic absorption spectrophotometry according to GB/T17138-1997, total Hg was determined using AFS, and total As was determined using silver diethyldithiocarbamate spectrophotometry. For plant samples, Pb was determined according to GB/T5009.12-2003 (determination of lead in food), Cd was determined according to GB/T5009.15-2003 (determination of cadmium in foods), As was determined according to GB/T5009.11-2003 (determination of total arsenic and abio-arsenic in foods), Cr was determined according to GB/T5009.123-2003(determination of chromium in foods), and Hg was determined using AFS
1.4 Results and discussion
In 2001, the emergence ratio and yield of mignonette were 1.2 times and 4.2 times those of the untreated control, respectively, and the emergence ratio and yield of forage corn were 5.6 times and 7.6 times those of the untreated control (Table 3).In 2002, the emergence ratio and yield of forage corn were 1.1-7.6 times and 1.1e6.8 times those of the untreated control, respectively, and the emergence ratio and yield of food corn were 1.1-3.7 times and 1.6-13.9 times those of the untreated control, respectively, depending on the soil ESP. The emergence ratios and yields of crops in soils with varying ESP are presented in Figs. 1-4
When examining Figs. 1 and 2, it is apparent that the emergence ratios of corns in experimental fields are higher than that in control fields, especially for soils with higher ESP. The emergence ratio of corns in the soils with high ESP was 70% in 2002, and it was 93.3% in 2003.It is apparent from Fig. 3 that the biomass yield of forage corns in the treated ?elds with high soil ESP reached 51 Mg ha 1, much higher than 7.5 Mg ha 1 in the control fields, and also higher than 32 Mg ha 1 in the control fields with mid soil ESP. It is also apparent from Fig. 4 that the seed yield of food corns in the treated fields with high soil ESP was 8618 kg ha 1, 8000 kg ha 1 higher than that in the control. This indicates that FGD byproducts are much more effective in fields with high soil ESP and produce a significant increase in plant yields. Compared with fields with low soil ESP, however, plant yields in fields with high ESP are still lower.
It is also apparent from Figs. 1e4 that the results for 2003 are superior to those for 2002. In 2003, the emergence ratio and yield of corns were 93.3% and 8618 kg ha 1 for high ESP soils, respectively. These results demonstrate that the barren land had been successfully changed into cultivatable soil. In 2005, the emergence ratio of alfalfa was 30e50% in the
experimental fields, and the yields were 1333e4335 kg ha 1, with the average 2079 kg ha 1. As the comparison, the emergence ratio and yield were almost zero in the control fields.The effect of the application of FGD byproducts on the concentrations of heavy metals in the crops and soils was assessed. The initial assessment involved 3 stages. The first stage involved the detection of concentrations of heavy metals in FGD byproducts (Table 1). Table 4 shows the concentrations of elements stipulated by Control Standards of Pollutants in Fly Ash for Agricultural Use (GB8173-1987) and Environmental Quality Standard for Soils (GB15618-1995).It is apparent from the tables that the concentrations of heavy metals in the FGD byproducts were far below the national standard limits for China: most were below the background levels of the soil.The second stage involved the analysis of concentrations of heavy metals in treated and untreated soils (Table 5). The concentrations of Cr, Pb, and As in treated soils with mid ESP increased relative to the control soils. The concentrations of Cd and Hg in soils with mid ESP and all analyzed elements in soils with high ESP decreased relative to the control soils.The concentrations of Pb, Cd, and Hg in soils of No. 2 experimental fields slightly increased relative to the control soils.The concentrations of all the heavy metals analyzed in the experimental treatments were far below the soil background levels regulated by Environmental Quality Standard for Soils(GB15618-1995).
The final stage involved the analysis of heavy metals in corn seeds and alfalfa (Table 6). No change was found in the concentration of heavy metals in the seeds of corns and alfalfa grown in the treated soils compared with those grown in the control soils. The results of this initial study indicate that the application of FGD byproducts does not contaminate the soil or crops grown in the soil, although further detailed studies are yet to be undertaken.
1.5 Conclusions
The amelioration of alkali soil using FGD byproducts sourced from power plants changes barren land into cultivatable soil, bringing about great social and economic benefits. The experimental results obtained for 3 consecutive years after the application of FGD byproducts in 2001 reveal that the emergence ratio and plant yield of crops were 1.1-7.6 timesand 1.1-13.9 times those of the untreated control, respectively, depending on the soil ESP. The concentrations of heavy metals in the treated soil and crops grown in the soil are far below the soil background levels and the tolerance limits stipulated by National Food Standards. The results of this research demonstrate that the amelioration of alkali soils using FGD byproducts is promising.
2 Macroscopic to microscopic studies of flue gas desulfurization byproducts for acid mine drainage mitigation
2.1 Introduction
The use of flue gas desulfurization (FGD) systems to reduce SO2 emissions has resulted in the generation of large quantities of byproducts. These and other byproducts are being stockpiled at the very time that alkaline materials having high neutralization potential are needed to mitigate acid mine drainage (AMD). FGD byproducts are highly alkaline materials composed primarily of unreacted sorbents (lime or limestone and sulfates and sulfites of Ca). Approximately 20 million tons of FGD material were generated by electric power utilities equipped with wet lime-limestone FGD systems according to the lastest calculation (l993). Less than 5% of this material has been put to beneficial use for agricultural soil amendments and for the production of wallboard and cement.
Four USGS projects are examining FGD byproduct use to address these concerns. These projects involve 1) calculating the volume of flue gas desulfurization (FGD) byproduct generation and their geographic locations in relation to AMD, 2) determining byproduct chemistry and mineralogy, 3) evaluating hydrology and geochemistry of atmospheric fluidized bed combustion byproduct as soil amendment in Ohio, and 4) analyzing microbial degradation of gypsum in anoxic limestone drains in West Virginia.
2.2 United states FGD data base
The Industrial Minerals Branch of the Office of Minerals Information (formerly the U.S. Bureau of Mines) at the USGS has developed a Geographic Information System (GIS) that can be used to provide information on the availability and proximity of FGD byproducts and potential markets, such as wallboard plants, portland cement industries, and AMD problem areas. With this information, we are able to assess the economic potential of FGD byproduct markets on a national basis for the first time.
The distribution of electric power utilities equipped with FGD units is widespread. FGD byproduct production and accumulation to the year 1998 was forecast by the Energy Information Administration. At current production rates, as much as 200 million metric tons of FGD materials will be generated and stored primarily in landfills by the year 2000. This is an enormous volume of highly alkaline material. An important objective, therefore, is to characterize FGD byproduct chemistry and mineralogy to identify beneficial and deleterious components.
2.3 Characterization of FGD feed limestone and byproducts
The USGS, the Kentucky Geological Survey, and a Kentucky utility have initiated a project to gather information on the chemistry and mineralogy of feed coal, feed limestone, fly ash, bottom ash, and FGD byproduct at a Kentucky power plant. Samples of each of these materials are being collected at monthly intervals. The wide variety of analyses on each include the concentration of as many as 50 elements; mineralogy (X-ray diffraction, optical petrography); modes of occurrence (scanning electron microscopy, microprobe analysis, selective leaching); organic geochemistry; radionuclide analysis; toxic characterization of leaching procedure (TCLP); and column leaching.
Results from this data base will be made available and are expected to provide insights into the influence of chemistry and mineralogy of the feed limestone and coal on the chemistry of FGD sludges. An important objective is to use the data to determine the relative reactivity of the various byproduct components in surface and ground water.
2.4 Surface and ground water characterization of FGD byproduct utilization at demonstration site in tuscarawas county, ohio
FGD byproducts were applied at an abandoned surface coal mine in Tuscarawas County, Ohio to neutralize AMD, learn about changes in water chemistry, and increase soil alkalinity to aid in revegetation. This research is a joint effort between the USGS Water Resources Division (Ohio District) and The Ohio State University.
Dry FGD byproduct was applied to the surface in late 1994 during reclamation of the 45-acre Fleming site. Pre-reclamation surface-water discharges from the site were acidic (pH 2.9 to 5.5) and erosion was severe owing to lack of vegetation. FGD materials were applied to six 1-acre test watersheds on bases of 4-feet-thick acidic mine spoil. Three replicates of 3 reclamation treatments were applied to each spoil surface, either as (1) standard reclamation practice of 8 in. of topsoil amended with ag-lime; (2) 8 in. of topsoil amended with 125 tons/acre dry FGD byproduct; or (3) 8 in. of topsoil amended with a blend of dry FGD byproduct and yard-waste compost. In addition, FGD materials were applied at a rate of 125 tons/acre to reworked minespoil in a buffer zone that surrounds the test plots. Physical, mineralogical, and engineering properties of FGD materials used at the Fleming site have been extensively investigated [3,4,5]. The dry FGD byproduct used in this study was produced by an atmospheric fluidized-bed boiler operating at a General Motors plant in Pontiac, Mich. The boiler uses coal and limestone produced in Ohio. Constituents having existing primary or secondary drinking water standards and therefore potential adverse affects on water quality if leached in sufficient quantities from the FGD byproduct include As (47 ppm), Cr (75 ppm), Ni (55 ppm), Pb (36 ppm), Se (11 ppm), and SO4 (18 to 21 weight percent as SO4). Paste pH of the FGD byproduct ranges from 10 to 12, and the CaCO3 equivalency ranges from 37.7 to 39.5 tons CaCO3/100 tons of byproduct.
Hydrogeology and geochemistry of the Fleming site were investigated by rock coring and whole-rock analysis, 35 soil-suction lysimeters and 20 monitoring wells, and surface and borehole geophysics. Lysimeters were installed at 1.5-4.5 ft depths, whereas wells were screened at about 30-100 ft depths. Water levels, specific conductance, and temperature have been measured hourly in 7 automated monitoring wells since June 1995. Because of high sulfate concentrations in both shallow ground water affected by AMD and in the FGD leachate, the isotopic composition of dissolved sulfate is being investigated as a possible tracer of FGD byproduct leachate.
Initial results indicate that the composition of surface water and shallow pore water have been affected by FGD byproduct leachate. Pore waters collected from lysimeters in the application area have pH values greater than 6.5, Fe concentrations less than 1.0 mg/L, sulfate concentrations on the order of 5,000 to 10,000 mg/L, and molar Mg:Ca ratios greater than 5, whereas pore-water samples from lysimeters installed outside the application area have lower pH values (4.4-5.7) and sulfate and dissolved solids concentrations that are a factor of 5 to 10 lower than those in samples from lysimeters inside the application area. These data are consistent with the hypothesis that alkaline leachate which infiltrate the unsaturated minespoil is neutralizing acidity produced by oxidation of pyrite. The result is near-neutral pH values and low dissolved iron and aluminum concentrations. High sulfate concentrations primarily reflect leaching of the gypsum component of the FGD material.
In contrast, ground water beneath the Fleming site typically has pH values of 5 to 6, dissolved Fe concentrations of several hundred mg/L, sulfate concentrations of several hundred to several thousand mg/L, and Mg:Ca molar ratios <1.0. These data suggest that leachate from the FGD byproduct has not reached an