油基岩屑焚烧过程钡的转化与环境风险研究
StudyonBariumTransformationandEnvironmentalRiskDuring Oil-based CuttingsIncineration
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摘要: 油基岩屑焚烧处置技术已被广泛应用,但油基岩屑焚烧尾渣的环境风险及其主要形成机制尚未得到广泛关注。本研究通过实际样品采集和实验室模拟等方式,结合多种表征方法,针对四川省天然气开采油基岩屑典型回转窑焚烧处置过程中钡的转化以及焚烧尾渣的环境风险特征开展了研究。研究表明,油基岩屑经焚烧后尾渣中钡浸出毒性水平大幅上升,这种现象的主要原因是油基岩屑中硫酸钡在800℃以上发生碳热还原反应生成硫化钡,并与氯化氢等反应产生氯化钡,这种还原转化过程主要发生在硫酸钡晶体颗粒表面,并最终形成了被可溶性钡外壳包裹的硫酸钡晶体颗粒。油基岩屑焚烧、燃煤锅炉协同处置以及水基岩屑、油基岩屑脱油干渣制烧结砖等还原性高温热处理过程均可能发生硫酸钡碳热还原转化,热处理过程钡的转化及固相高可溶性钡环境风险应得到广泛关注和有效防控,建议从标准政策制定、风险源头防控和尾渣末端治理等方面进行控制。Abstract: The incineration technology of oil-based cuttings has been widely used. However, the environmental risks and main formation mechanism of oil-based rock cuttings incineration tailings have not been widely concerned.Through actual sample collection and laboratory simulation, combined with a variety of characterization methods, this study conducted a study on the conversion of barium and the environmental risk characteristics of incineration tailings in the typical rotary kiln incineration disposal process of oil-based rock cuttings from natural gas exploitation in Sichuan Province.The research results showed that the barium leaching toxicity level in the incineration tailings of oil-based cuttings was incinerated increases significantly. The main reason for this phenomenon was proved that barium sulfate in oil-based cuttings was transformed to barium sulfide by carbothermic reduction reaction above 800℃, and reacted with hydrogen chloride to produce barium chloride. This reduction conversion process mainly occured on the surface of barium sulfate crystal particles, and these barium sulfate crystal particles wrapped by soluble barium shells were finally formed. Carbothermic reduction conversion of barium sulfate may occur in reductive high-temperature heat treatment processes such as oil-based cuttings incineration, co-processing of oil-based cuttings in coal-fired boiler, and water-based cuttings and oil-based cuttings deoiled dry residue making sintered bricks. The conversion of barium during heat treatment and the environmental risk of high-soluble barium in solid phase should be widely concerned and effectively prevented. The control over this problem from the aspects of standard policy formulation, risk source prevention and control, and tailings terminal treatment were recommended in this paper.
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Key words:
- oil-based cutting /
- incineration /
- barium /
- carbothermic reduction
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