本文選題：赤泥 + 鈧��； 參考：《北京科技大學(xué)》2017年博士論文

【摘要】：赤泥是氧化鋁生產(chǎn)過程中排出的固體廢棄物。在大多數(shù)赤泥中都含有少量的稀貴金屬元素,所以它也是一種具有重要潛在價(jià)值的二次資源。目前世界上的赤泥累積量已經(jīng)超過27億噸。對(duì)于如何有效處理赤泥已經(jīng)迫在眉睫。從赤泥中回收鈉、鋁、鐵等主要元素的同時(shí),回收鈧等其他稀貴元素吸引越來越多的研究人員關(guān)注。本文在綜述赤泥的產(chǎn)生過程、物化特性及其應(yīng)用現(xiàn)狀,系統(tǒng)論述國(guó)內(nèi)外有價(jià)元素的冶金工藝流程及溶液稀有元素萃取及反萃取的機(jī)理的基礎(chǔ)上,針對(duì)山東某氧化鋁廠拜耳法產(chǎn)出赤泥,提出了一種高效選擇性分離提取鈧和鈉的新工藝。赤泥中鈧與主元素礦物的賦存特性直接決定了鈧提取工藝的選擇,所以本文首先運(yùn)用二次飛行時(shí)間質(zhì)譜(ToF-SIMS)和電子探針(EPMA),研究了赤泥中元素Sc和Ga與主元素Fe、Al、Si、Ti以及Ca的親和行為。通過二次飛行時(shí)間質(zhì)譜、電子探針元素分布圖以及電子探針微區(qū)量化分析表明,在赤泥礦相中Sc元素與Fe、Al、Ti、Si表現(xiàn)出了一定的親和行為,并且其親和順序應(yīng)按照TiFeAlSi進(jìn)行。Ga元素與Fe、Al、Ti、Ca、Si表現(xiàn)出了一定的親和行為,并且其親和順序應(yīng)按照FeAlTiCaSi進(jìn)行。鈧的載體礦物主要是銳鈦礦、赤鐵礦和針鐵礦。在銳鈦礦中,異價(jià)類質(zhì)同象方式4Sc~(3+)→3Ti~(4+)是其主要嵌入銳鈦礦的方式。與赤鐵礦或針鐵礦的類質(zhì)同象方式Sc~(3+)→Fe~(3+)相比,完全不同。富硅礦物的石英相中也存在部分鈧。與Sc元素不同的是鎵在各礦物中的分布相對(duì)均勻,僅與鐵鋁略微表現(xiàn)出更為密切的配位關(guān)系,即鎵在巖相形成過程中可以較容易的置換赤鐵礦、針鐵礦和三水鋁石晶體中被Fe~(3+)和Al~(3+)占據(jù)的位置。赤泥中Na離子的能否去除對(duì)后續(xù)赤泥的利用或元素綜合提取有重大影響。通過TG-DTA、QXRD、FTIR、SEM等分析,探究了隨爐冷卻、空冷、水淬以及液氮冷卻四種不同冷卻方式對(duì)活化焙燒赤泥處理后鈉離子浸出的影響。研究結(jié)果表明,冷卻速率越快,鈉離子的浸出率相對(duì)越高。因此,在四種冷卻方式中同等條件下,液氮冷卻活化焙燒赤泥樣品的浸出液中鈉離子濃度最高,其濃度可高達(dá)1202 mg.L-1(～25 w%回收率)。其原因是活化焙燒中,新相Na_2Ca(CO_3)_2的出現(xiàn)在較快冷卻速率的樣品中,該相可以容易地溶于水溶液中。部分霞石脫硅產(chǎn)物轉(zhuǎn)變?yōu)镹aCaHSiO_4和鈉鉀霞石。在液氮冷卻樣品中Ca(OH)_2的濃度增加到～4.8wt%,它在一定程度上有利于霞石和NaCaHSiO_4的溶解。非晶相量隨冷卻速率增快而增大。在隨爐冷卻樣品中,非晶相量?jī)H為～4.1 wt%;而在液氮冷卻樣品中,非晶相量卻增加到了～13.5 wt%,非晶相量的增加無疑會(huì)促進(jìn)鈉離子的浸出。在微觀形態(tài)方面,較快冷卻速率樣品主要呈蓬松的片狀或絮狀,這減弱了焙燒后赤泥物相的團(tuán)聚程度;比表面積SSA值的相對(duì)增加,使浸出液與顆粒的有效接觸面積也將增大。不同冷卻方式下,微觀形態(tài)變化亦對(duì)浸出有一定促進(jìn)影響。綜合可見焙燒樣品較快冷卻速率有利于鈉離子的浸出。鈧、鈉與鐵的分離通過硫酸化焙燒水浸工藝實(shí)現(xiàn),該工藝相比于傳統(tǒng)的直接酸浸工藝顯示出極高的選擇性與可操作性。主要內(nèi)容包括探究拜耳赤泥中鈣、鐵、鋁、硅、鈉、鈦、鈧和鎵在焙燒過程中物相轉(zhuǎn)變規(guī)律,以及探究焙燒溫度、焙燒時(shí)間、硫酸添加量、浸出溫度、浸出時(shí)間、浸出液固比對(duì)這些元素浸出行為的影響。研究結(jié)果表明,焙燒溫度和焙燒時(shí)間是能否選擇性的從赤泥中回收鈧和鈉的最主要影響因素;另外,較高的浸出溫度也會(huì)對(duì)鐵離子的浸出產(chǎn)生負(fù)面影響。在焙燒過程中,鈉離子對(duì)金屬硫酸鹽的分解具有抑制作用,并且改變鐵鋁金屬硫酸鹽的分解順序。研究結(jié)論表明,硫酸鹽的分解順序如下:TiOSO_4Ga_2(SO_4)_3Fe_2(SO_4)_3NaFe(SO_4)_2NaAl(SO_4)_2～Al_2(SO_4)_3Na_3Sc(SO_4)_3Na_2SO_4CaSO_4。在此,需要強(qiáng)調(diào)的是在完成水洗滌焙燒料后,固液分離步驟可以非常順利的進(jìn)行。在最佳焙燒和浸出條件下,有95 wt%的 Na+,～60wt%的 Sc 以[Sc(H_2O)x(SO4)n]3-2(x≤6)形式被浸出,同時(shí)伴隨有1wt%的Fe~(3+)、7wt%的Al~(3+)、～29wt%的Ca2+和3 wt%Si~(4+)較低雜質(zhì)元素浸出,而Ti~(4+)和Ga~(3+)不被浸出,有效實(shí)現(xiàn)了赤泥中鈧、鈉與鐵、鈦、硅等元素的分離。浸出后的尾渣可以考慮作為高爐煉鐵或建材原料。本文還研究了硫酸化焙燒赤泥浸出液中Sc的萃取分離。比較磷酸類萃取劑P204、P507和羧酸類萃取劑Versatic acid 10,發(fā)現(xiàn)P204對(duì)鈧表現(xiàn)出較好的萃取性能。萃取實(shí)驗(yàn)的最佳萃取工藝條件是:水相與有機(jī)相比值(A:O)為10:1;萃取溫度為15℃;萃取系組成為P204/磺化煤油(1%v/v)。在該條件下,～97%的Sc可被提取出來,同時(shí)得到硫酸鈉副產(chǎn)物。另外,0.35～0.5的硫酸溶液可用于萃取有機(jī)相洗滌;反萃取條件可用2 mol·L-1 NaOH溶液進(jìn)行。
[Abstract]:Red mud is a solid waste in the process of alumina production. In most red mud, a small amount of rare and precious metals are contained, so it is also a two resource with important potential value. The accumulation of red mud in the world is over 27 million tons now. It is imminent to recover red mud from the red mud and recycle it from red mud. The recovery of scandium and other rare elements attract more and more researchers at the same time, such as sodium, aluminum, iron and other major elements. This article reviews the production process, physicochemical properties and application status of red mud, and systematically discusses the metallurgical process of the valuable elements at home and abroad and the mechanism of extraction and reverse extraction of rare elements in the solution. A new process of selective separation and extraction of scandium and sodium by high efficiency and selective separation of red mud from the Bayer process in a alumina plant is proposed. The selection of scandium extraction process is directly determined by the occurrence characteristics of scandium and the main element minerals in red mud. Therefore, the two time time of flight mass spectrometry (ToF-SIMS) and electron probe (EPMA) are used to study the elements Sc and G in the red mud. The affinity behavior of a with the main elements Fe, Al, Si, Ti and Ca. Through two time flight time mass spectrometry, electron probe element distribution and electron microprobe microquantization, it is shown that the Sc elements in the red mud are shown to be compatible with Fe, Al, Ti, Si, and their affinity and order should be performed according to TiFeAlSi. A certain affinity behavior, and its affinity sequence should be carried out according to FeAlTiCaSi. The carrier minerals of scandium are mainly anatase, hematite and goethite. In anatase, 4Sc~ (3+) to 3Ti~ (4+) is the main form of anatase in anatase. Compared with Sc~ (3+) to Fe~ (3+) in the same way of hematite or goethite. Unlike the Sc element, the distribution of gallium in each mineral is relatively homogeneous and is only a little more closely related to the iron and aluminum. That is, gallium can be easier to replace hematite in the formation of the lithofacies, and Fe~ (3+) and Al~ (3+) in the crystals of the goethite and trihydrate. The removal of Na ions in red mud has a significant influence on the utilization of red mud and the comprehensive extraction of elements. Through the analysis of TG-DTA, QXRD, FTIR and SEM, the effects of four different cooling methods on the leaching of sodium ion after the activation roasting red mud are investigated with the cooling, air cooling, water quenching and liquid nitrogen cooling. The results show that the cooling is cooled. The faster the rate, the higher the leaching rate of sodium ions. Therefore, under the same conditions in the four cooling methods, the concentration of sodium ion in the leaching solution of the liquid nitrogen cooling activated red mud is the highest, and the concentration can be as high as 1202 mg.L-1 (to 25 w% recovery). The reason is that the new phase Na_2Ca (CO_3) _2 appears in the rapid cooling rate during the activation roasting. In the sample, the phase can be easily dissolved in aqueous solution. Some nepheline desilication products are converted to NaCaHSiO_4 and sodium potassium nepheline. The concentration of Ca (OH) _2 increases to 4.8wt% in the liquid nitrogen cooling samples. It is beneficial to the dissolution of nepheline and NaCaHSiO_4 to a certain extent. The amorphous phase increases with the cooling rate. The crystalline phase amount is only 4.1 wt%, but in the liquid nitrogen cooling samples, the amorphous phase increases to 13.5 wt%. The increase of the amorphous phase will undoubtedly promote the leaching of sodium ions. In the micromorphology, the rapid cooling rate samples are mainly fluffy flake or floc, which weakens the aggregation degree of the red mud phase after the calcination; the specific surface area SSA value. The relative increase of the effective contact area of the leaching solution and the particle will also increase. Under the different cooling methods, the micromorphological changes also have a certain effect on the leaching. The rapid cooling rate of the comprehensive visible roasting sample is beneficial to the leaching of sodium ions. The separation of scandium and sodium and iron through the sulphate roasting and water leaching process is compared with the traditional process. The direct acid leaching process shows high selectivity and maneuverability. The main contents include exploring the phase transformation of calcium, iron, aluminum, aluminum, silicon, sodium, titanium, scandium and gallium during the roasting process, and exploring the roasting temperature, calcination time, sulphuric acid addition, leaching temperature, leaching time, leaching behavior of leaching liquid and solid ratio. The results show that the baking temperature and the calcination time are the most important factors that can selectively recover scandium and sodium from the red mud. In addition, the higher leaching temperature can also have a negative effect on the leaching of iron ions. During the calcination process, the sodium ion has a inhibitory effect on the decomposition of metal sulfate and changes the iron and aluminum metal. The decomposition order of sulfate is found to show that the decomposition order of sulfate is as follows: TiOSO_4Ga_2 (SO_4) _3Fe_2 (SO_4) _3NaFe (SO_4) _2NaAl (SO_4) _2 to Al_2 (SO_4) _3Na_3Sc. It is necessary to emphasize that after completing the washing and roasting material, the step of solid-liquid separation can be carried out very smoothly. In the best roasting and leaching process. Under the conditions, 95 wt% Na+, 60wt% Sc are leached in the form of [Sc (H_2O) x (SO4) n]3-2 (x < < 6), and the leaching of 1wt% Fe~ and 3 lower impurity elements, and the separation of scandium, sodium and iron, titanium, silicon and other elements in the red mud. The tail slag can be considered as a material for blast furnace ironmaking or building materials. This paper also studied the extraction and separation of Sc in the leaching solution of the red mud by sulfuric acid roasting. Compared with the phosphoric acid extractant P204, P507 and the carboxylic acid extractant Versatic acid 10, it was found that P204 showed good extraction performance for scandium. The optimum extraction conditions for the extraction were as follows: the water phase and the available extraction conditions The ratio of the phase to phase (A:O) is 10:1, the extraction temperature is 15 C, the extraction system is composed of P204/ sulfonated kerosene (1%v/v). Under this condition, 97% of Sc can be extracted and the sodium sulphate by-product is obtained. In addition, 0.35 ~ 0.5 sulfuric acid solution can be used to extract organic phase washing; the extraction conditions can be carried out by 2 mol. L-1 NaOH solution.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：X758;TF803.23

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