TW201502072A - Method for forming calcium sulfate dihydrate from desulfurized limestone byproducts - Google Patents
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本發明係關於一種形成二水硫酸鈣之方法，尤指將石灰石脫硫反應後所產生之副產物所包含的硫酸鈣、氫氧化鈣、氧化鈣以及碳酸鈣同時轉換為具有經濟價值之高純度二水硫酸鈣之方法。
The invention relates to a method for forming calcium sulfate dihydrate, in particular to convert calcium sulfate, calcium hydroxide, calcium oxide and calcium carbonate contained in by-products produced by desulfurization reaction of limestone into high purity with economic value. Method of calcium sulfate dihydrate.
石灰石脫硫副產物之形成係來自於使用高溫循環式流體化床發電鍋爐(Circulating Fluidized Bed Boiler，CFB)以燃燒煤、石油焦或其他含硫之燃料來發電的過程中，為了避免燃燒後高含硫量之燃料產生硫氧化物過量排放，故添加石灰石進行脫硫，而所產生之副產物即為CFB石灰石脫硫副產物。The formation of limestone desulfurization by-products comes from the use of a circulating fluidized bed boiler (CFB) to burn coal, petroleum coke or other sulfur-containing fuels to generate electricity, in order to avoid high combustion The sulfur-containing fuel produces excessive emission of sulfur oxides, so limestone is added for desulfurization, and the by-product produced is CFB limestone desulfurization by-product.
CFB石灰石脫硫副產物具有低強度的特性，有利用於強度要求不高的相關土木營造材料或產品之潛力，例如園藝花圃、路基填土工程等，或者是在農業上用以改良受酸雨汙染之酸性土壤，或是運用於一般防火石膏板上；CFB石灰石脫硫副產物與軟質黏性土壤攪拌混和後，會產生硝化反應、氫氧離子分解及化學反應等，此一連串的反應過程將因吸水、膨脹、放熱、離子交換、膠結及碳酸化等作用，改變土壤物理及化學性質。The CFB limestone desulfurization by-product has low strength properties and is beneficial for the potential of related civil construction materials or products with low strength requirements, such as horticultural flower buds, roadbed filling works, etc., or for improving acid rain pollution in agriculture. The acidic soil is applied to the general fireproof gypsum board; after the CFB limestone desulfurization by-product is mixed with the soft sticky soil, nitrification reaction, hydroxide ion decomposition and chemical reaction will occur, and the series of reaction processes will be caused by Water absorption, expansion, exotherm, ion exchange, cementation and carbonation, etc., change the physical and chemical properties of the soil.
然而，CFB石灰石脫硫副產物之酸鹼值常超過11.0，係為具有腐蝕性的強鹼物質，即便是在於土木營造或是農業上再利用，很容易造成使土壤過度鹼化而草木難生，並且有汙染地下水源之虞；同時直接將石灰石脫硫副產物混入水泥當建材時，乾燥後也有可能逐漸形成礬石，造成建築物膨脹而產生裂痕之問題；再者其具強鹼腐蝕性，對人體也會造成眼睛及皮膚的傷害。因此也有視之為無法做有價值再利用之廢棄物之看法。However, the pH value of CFB limestone desulfurization by-products often exceeds 11.0, which is a corrosive strong alkali substance. Even if it is built in civil engineering or reused in agriculture, it is easy to cause excessive alkalization of the soil and difficulty in vegetation. And there is pollution of the groundwater source; at the same time directly mixing limestone desulfurization by-products into the cement as building materials, it is also possible to gradually form vermiculite after drying, causing the building to expand and cause cracks; and further, it has strong alkali corrosion. It can also cause eye and skin damage to the human body. Therefore, there is also a perception that it is impossible to make valuable waste for reuse.
因此，若能將石灰石脫硫副產物之成分進行轉化而形成其他成分，則可使石灰石脫硫副產物更具有回收之價值，必且可以避免其被任意傾倒而產生的環境汙染問題。Therefore, if the components of the limestone desulfurization by-product can be converted to form other components, the limestone desulfurization by-product can be more valuable for recovery, and environmental pollution problems caused by arbitrary dumping can be avoided.
將石灰石脫硫副產物轉化為二水硫酸鈣係為一個可行的方向。二水硫酸鈣俗稱為石膏，係為重要的工業原料，具有做為膠凝材料和建築製品等用途。而若要將石灰石脫硫副產物轉化為二水硫酸鈣，習知的方法係將石灰石脫硫副產物浸置於水池中進行水化反應，此時石灰石脫硫副產物當中的硫酸鈣會與水分子反應產生二水硫酸鈣，但反應速率相當慢，且氧化鈣、碳酸鈣以及氫氧化鈣等其他成分並無法直接形成二水硫酸鈣。The conversion of limestone desulfurization by-products to calcium sulfate dihydrate is a viable direction. Calcium sulphate dihydrate, commonly known as gypsum, is an important industrial raw material and has applications as a cementitious material and a building product. If the limestone desulfurization by-product is to be converted into calcium sulfate dihydrate, the conventional method is to immerse the limestone desulfurization by-product in the pool for hydration reaction, at which time the calcium sulfate in the limestone desulfurization by-product will The water molecule reacts to produce calcium sulfate dihydrate, but the reaction rate is rather slow, and other components such as calcium oxide, calcium carbonate, and calcium hydroxide cannot directly form calcium sulfate dihydrate.
並且，石灰石脫硫副產物的成分相當複雜而並非僅含有硫酸鈣，其所具有的氧化鈣在與水分子反應時，會產生氫氧化鈣，致使水溶液呈強鹼性。而硫酸鈣所轉化而成的二水硫酸鈣亦很難從其他成分中分離出來，因此面臨著轉化純度不高且溶液呈強鹼性的問題。Moreover, the composition of the limestone desulfurization by-product is rather complicated and does not contain only calcium sulfate. The calcium oxide which it has has calcium hydroxide when it reacts with water molecules, so that the aqueous solution is strongly alkaline. The calcium sulfate dihydrate converted by calcium sulfate is also difficult to separate from other components, so it faces the problem that the conversion purity is not high and the solution is strongly alkaline.
故如何方能對組成複雜之石灰石脫硫副產物進行全面轉化之反應流程，以確實將原本難以處理之石灰石脫硫副產物轉化為可資利用的高純度二水硫酸鈣，即是本發明所要解決的一道課題。
Therefore, how can the reaction process for the comprehensive conversion of complex limestone desulfurization by-products be carried out to convert the limestone desulfurization by-products that were originally difficult to process into high-purity calcium sulfate dihydrate, which is required by the present invention. A problem solved.
本發明之主要目的，係提供一種石灰石脫硫副產物形成二水硫酸鈣之方法，其可將混合多種鈣化合物之石灰石脫硫副產物一次性地進行反應，不需要將氧化鈣、硫酸鈣、氫氧化鈣等物質做分離而各別處理，具有便利性。The main object of the present invention is to provide a method for forming a limestone desulfurization by-product to form calcium sulfate dihydrate, which can react a limestone desulfurization by-product mixed with a plurality of calcium compounds in one time, without requiring calcium oxide, calcium sulfate, It is convenient to separate and treat substances such as calcium hydroxide.
本發明之次要目的，係提供一種石灰石脫硫副產物形成二水硫酸鈣之方法，其轉化所需時間短，不需曠日費時等待特定物質發生反應。A secondary object of the present invention is to provide a method for forming a limestone desulfurization by-product to form calcium sulfate dihydrate, which requires a short conversion time and does not require time-consuming waiting for a specific substance to react.
本發明之再一目的，係提供一種石灰石脫硫副產物形成二水硫酸鈣之方法，其可確實處理氫氧化鈣之轉化流程，避免其混雜於二水硫酸鈣中而導致分離上的困難或是造成產物呈強鹼性等問題。A further object of the present invention is to provide a method for forming a limestone desulfurization by-product to form calcium sulfate dihydrate, which can surely process the conversion process of calcium hydroxide, avoiding mixing in calcium sulfate dihydrate and causing difficulty in separation or It is a problem that the product is strongly alkaline.
本發明之更一目的，係提供一種石灰石脫硫副產物形成二水硫酸鈣之方法，其可確保所產生之二水硫酸鈣具有高純度，能直接做進一步的產業利用。A further object of the present invention is to provide a method for forming a limestone desulfurization by-product to form calcium sulfate dihydrate, which ensures that the calcium sulfate dihydrate produced has high purity and can be directly utilized for further industrial use.
故為了達到上述之目的，本發明揭示了一種石灰石脫硫副產物形成二水硫酸鈣之方法，該石灰石脫硫副產物係由石灰石CFB脫硫反應後所產生，其係包含步驟：將已浸泡於水或乾燥之石灰石脫硫副產物水溶液加入一溶液並攪拌反應，該溶液係包含硫酸根離子或亞硫酸根離子；維持溶液之酸鹼值小於或等於8；反應中或反應後分層該溶液，使該溶液形成一含懸浮物層以及一沉澱物層；分離該懸浮物層以及該沉澱物層。如此，原本組成複雜之石灰石脫硫副產物即可全面地轉化為高純度的二水硫酸鈣。
Therefore, in order to achieve the above object, the present invention discloses a method for forming a limestone desulfurization by-product to form calcium sulfate dihydrate. The limestone desulfurization by-product is produced by desulfurization reaction of limestone CFB, and the method comprises the steps of: immersing Adding a solution to the aqueous solution of water or dried limestone desulfurization by-product and stirring the reaction, the solution containing sulfate ion or sulfite ion; maintaining the pH value of the solution is less than or equal to 8; layering during or after the reaction The solution is such that the solution forms a suspension-containing layer and a precipitate layer; the suspension layer and the precipitate layer are separated. In this way, the limestone desulfurization by-product which is originally composed of complex can be completely converted into high-purity calcium sulfate dihydrate.
S1~S5‧‧‧步驟
S1~S5‧‧‧Steps
第一圖：其係為本發明之步驟流程圖。
First Figure: It is a flow chart of the steps of the present invention.
為使本發明之特徵及所達成之功效有更進一步之瞭解與認識，謹佐以較佳之實施例及配合詳細之說明，說明如後：For a better understanding and understanding of the features and advantages of the present invention, the preferred embodiments and the detailed description are described as follows:
首先，請參考第一圖，其係為本發明之步驟流程圖；如圖所示，其係包含步驟：
步驟S1：浸泡該石灰石脫硫副產物於水中，形成一水化石灰石脫硫副產物；
步驟S2：將該水化石灰石脫硫副產物水溶液加入一溶液，該溶液係包含硫酸根離子或亞硫酸根離子；
步驟S3：於反應中攪拌，維持溶液之酸鹼值小於或等於8；
步驟S4：反應中或反應後分層該溶液，使該溶液形成一含懸浮物層以及一沉澱物層；以及
步驟S5：分離該懸浮物層以及該沉澱物層。First, please refer to the first figure, which is a flow chart of the steps of the present invention; as shown in the figure, it includes the steps:
Step S1: soaking the limestone desulfurization by-product in water to form a hydrated limestone desulfurization by-product;
Step S2: adding the aqueous solution of the hydrated limestone desulfurization by-product to a solution containing sulfate ions or sulfite ions;
Step S3: stirring in the reaction, maintaining the pH value of the solution is less than or equal to 8;
Step S4: layering the solution during or after the reaction to form a suspension-containing layer and a precipitate layer; and step S5: separating the suspension layer and the precipitate layer.
本發明中所處理的石灰石脫硫副產物，係來自於石灰石脫硫反應後所產生之物質，其主要成分係為硫酸鈣、氫氧化鈣、氧化鈣以及碳酸鈣，相當複雜而不易處理。本發明於步驟S1中，將石灰石脫硫副產物沉浸於水中，使之進行水化反應，生成了水化石灰石脫硫副產物。在此階段，石灰石脫硫副產物當中的氧化鈣會與水分子反應形成氫氧化鈣(式一)，而硫酸鈣則與水分子反應生成二水硫酸鈣(式二、三)。
此時式二之反應速率遠較式一來得緩慢，因此在進行水化反應6-60小時後，所形成之水化石灰石脫硫副產物係以氧化鈣所形成之氫氧化鈣、碳酸鈣、未反應完之氧化鈣、未反應完之硫酸鈣、以及些許二水硫酸鈣所組成。At this time, the reaction rate of Formula 2 is much slower than that of Formula 1, so after 6 to 60 hours of hydration reaction, the formed hydrated limestone desulfurization by-product is calcium hydroxide and calcium carbonate formed by calcium oxide. It consists of unreacted calcium oxide, unreacted calcium sulfate, and a little calcium sulfate dihydrate.
接著，再將水化石灰石脫硫副產物水溶液移至一反應槽中，並加入另一溶液，此溶液係包含了硫酸根離子(SO4 2- )或亞硫酸根離子(SO3 2- )，本發明於此可使用濃度為0.1~3.0M之硫酸水溶液，可適度地配合攪拌而提升其反應效率。Next, the aqueous solution of the hydrated limestone desulfurization by-product is moved to a reaction tank, and another solution is added, which contains sulfate ion (SO 4 2- ) or sulfite ion (SO 3 2- ) In the present invention, an aqueous sulfuric acid solution having a concentration of 0.1 to 3.0 M can be used, and the reaction efficiency can be improved by appropriately mixing with stirring.
此時，硫酸與碳酸鈣發生反應而產生二氧化碳(式四)，因此有冒泡的情況發生，並且產生硫酸鈣；步驟S1中若有殘留之氧化鈣則與硫酸溶液中的水分子反應而生成氫氧化鈣(前述式一)，並配合原具有之氫氧化鈣而使溶液之酸鹼值上升，因此本發明透過使用酸鹼質偵測器之監控，在酸鹼值上升超過7時，使用持續加入具有硫酸根離子或亞硫酸根離子之水溶液之方法，例如讓硫酸與氫氧化鈣反應(式五)，讓酸鹼值能夠保持於8以下，並且轉化為二水硫酸鈣(式三)。
本發明中所使用之石灰石脫硫副產物原本包含了不同比例的硫酸鈣、氫氧化鈣、氧化鈣及碳酸鈣。以本實施例說明，石灰石脫硫副產物含重量百分比55~65%之硫酸鈣、重量百分比15~25%之氫氧化鈣、重量百分比5~15%之氧化鈣以及重量百分比5~15%之碳酸鈣，而在經過上述數個反應式的作用之下，硫酸鈣轉化為二水硫酸鈣；氧化鈣與水反應生成氫氧化鈣，而氫氧化鈣再與硫酸反應產生鈣離子與硫酸鈣根離子，進而再轉化為二水硫酸鈣；至於碳酸鈣，則是與硫酸反應後生成硫酸鈣，再轉化為二水硫酸鈣。The limestone desulfurization by-products used in the present invention originally contain different ratios of calcium sulfate, calcium hydroxide, calcium oxide and calcium carbonate. In this embodiment, the limestone desulfurization by-product contains 55 to 65% by weight of calcium sulfate, 15 to 25% by weight of calcium hydroxide, 5 to 15% by weight of calcium oxide, and 5 to 15% by weight. Calcium carbonate, and under the action of the above several reaction formulas, calcium sulfate is converted into calcium sulfate dihydrate; calcium oxide reacts with water to form calcium hydroxide, and calcium hydroxide reacts with sulfuric acid to produce calcium ions and calcium sulfate roots. The ions are further converted into calcium sulfate dihydrate; as for calcium carbonate, it is reacted with sulfuric acid to form calcium sulfate, which is then converted into calcium sulfate dihydrate.
反應槽反應數分鐘後，停止進行攪拌，將溶液靜置而讓沉降發生。溶液由上至下可分別區分為懸浮物層以及沉澱物層。接著利用蠕動幫浦將溶液中懸浮物抽出，並進行抽氣過濾，將懸浮物分離，而其中的濾液可導回反應槽溶液中繼續反應或棄置，重複相同的步驟而利用抽氣過濾取出懸浮物，直至懸浮物不再產生為止。After the reaction tank was reacted for several minutes, stirring was stopped, and the solution was allowed to stand to allow sedimentation to occur. The solution can be divided into a suspended layer and a precipitate layer from top to bottom. Then, using the peristaltic pump to extract the suspended matter in the solution, and performing suction filtration to separate the suspended matter, and the filtrate therein can be returned to the reaction tank solution to continue the reaction or disposed, and the same steps are repeated to extract and suspend by suction filtration. Things until the suspension is no longer produced.
將懸浮物與沉澱物進行X光繞射分析，可發現懸浮物與沉澱物之晶型與二水硫酸鈣之晶型相符。另外再將懸浮物以及沉澱物進行熱重分析，並與二水硫酸鈣標準品之熱重分析圖相比較，估算沉澱物及懸浮物中二水硫酸鈣的比例。由分析結果得知，二水硫酸鈣標準品脫去結晶水造成的重量損失為20.6%，而懸浮物、粒徑介於0.5 mm ~ 1 mm沉澱物、以及粒徑大於1mm的沉澱物在此階段的熱重損失分別為19.66%、19.78%、19.64%。若依比例換算推測，懸浮物、粒徑介於0.5 mm ~ 1 mm沉澱物、以及粒徑大於1 mm的沉澱物中的二水硫酸鈣比例分別為95.44%、98.90%、95.34%。此外，懸浮物與沉澱物僅在100℃以下及800℃以上有重量損失，100℃以下的重量損失是由於二水硫酸鈣脫去結晶水變成無水硫酸鈣，而繼續加熱至800℃，無水硫酸鈣開始熱分解成氧化鈣造成此階段的重量損失。因此，可確認懸浮物及沉澱物皆為高純度的二水硫酸鈣，並無氫氧化鈣及碳酸鈣殘存。X-ray diffraction analysis of the suspended matter and the precipitate showed that the crystal form of the suspended matter and the precipitate conformed to the crystal form of calcium sulfate dihydrate. In addition, the suspended solids and the precipitate were subjected to thermogravimetric analysis, and the proportion of calcium sulfate dihydrate in the precipitate and the suspension was estimated by comparison with the thermogravimetric analysis of the calcium sulfate dihydrate standard. According to the analysis results, the weight loss caused by the removal of the crystal water from the calcium sulfate dihydrate standard is 20.6%, and the suspended matter, the precipitate having a particle diameter of 0.5 mm to 1 mm, and the precipitate having a particle diameter of more than 1 mm are here. The thermogravimetric losses at the stage were 19.66%, 19.78%, and 19.64%, respectively. According to the proportional conversion, the proportion of suspended solids, precipitates with a particle size of 0.5 mm to 1 mm, and calcium sulfate dihydrate with a particle size of more than 1 mm were 95.44%, 98.90%, and 95.34%, respectively. In addition, the suspended solids and precipitates have weight loss only below 100 ° C and above 800 ° C. The weight loss below 100 ° C is due to the removal of crystal water from calcium sulfate dihydrate to anhydrous calcium sulfate, and heating to 800 ° C, anhydrous sulfuric acid. Calcium begins to thermally decompose into calcium oxide causing weight loss at this stage. Therefore, it was confirmed that both the suspended matter and the precipitate were high-purity calcium sulfate dihydrate, and no calcium hydroxide or calcium carbonate remained.
配合透過上述之步驟，本發明考量到以石灰石脫硫副產物本身組成物的複雜性，且各成分難以進行分離之下，因此對石灰石脫硫副產物做統一性的處理，並且在反應過程中對不同成分所發生之反應做適當的回饋，而確保各種組成成分最終都能形成高純度的二水硫酸鈣。其不但所需時間短暫，而且解決了強鹼性的氫氧化鈣對水化石灰石脫硫副產物後續處理的問題；在兼具了多個面向之效益之下，本發明無疑提供了一種具實用與環保價值之石灰石脫硫副產物形成二水硫酸鈣之方法。In combination with the above steps, the present invention considers the complexity of the composition of the limestone desulfurization by-product itself, and the components are difficult to separate, so the limestone desulfurization by-products are uniformly treated, and during the reaction. Appropriate feedback on the reactions of different components ensures that the various components ultimately form high-purity calcium sulfate dihydrate. It not only takes a short time, but also solves the problem of the subsequent treatment of the hydrated limestone desulfurization by-product by the strong alkaline calcium hydroxide; the invention undoubtedly provides a practical solution under the multiple benefits. A method of forming calcium sulfate dihydrate with a by-product of limestone desulfurization of environmental value.
惟以上所述者，僅為本發明之較佳實施例而已，並非用來限定本發明實施之範圍，舉凡依本發明申請專利範圍所述之形狀、構造、特徵及精神所為之均等變化與修飾，均應包括於本發明之申請專利範圍內。
The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and the variations, modifications, and modifications of the shapes, structures, features, and spirits described in the claims of the present invention. All should be included in the scope of the patent application of the present invention.
S1~S5‧‧‧步驟 S1~S5‧‧‧Steps
Claims (6)
浸泡該石灰石脫硫副產物於水中，形成一水化石灰石脫硫副產物；
將該水化石灰石脫硫副產物水溶液加入一溶液，該溶液係包含硫酸根離子或亞硫酸根離子；
攪拌反應持續加入硫酸根離子或亞硫酸根離子，維持溶液之酸鹼值小於或等於8；以及
停止攪拌並分離該溶液，使該溶液形成一懸浮物層以及一沉澱物層。A method for forming a limestone desulfurization by-product to form calcium sulfate dihydrate, the limestone desulfurization by-product produced by a limestone desulfurization reaction, comprising the steps of:
Soaking the limestone desulfurization by-product in water to form a hydrated limestone desulfurization by-product;
Adding an aqueous solution of the hydrated limestone desulfurization by-product to a solution containing a sulfate ion or a sulfite ion;
The stirring reaction is continued by adding a sulfate ion or a sulfite ion to maintain the pH value of the solution to be less than or equal to 8; and the stirring is stopped and the solution is separated to form a suspension layer and a precipitate layer.
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