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Considering that the low recovery efficiency and the massive loss of valuable metals by the traditional pyrometallurgical process smelting low‒nickel matte. Therefore, this paper focuses on studying the optimal process parameters and the mechanism of sulphation roasting followed by water leaching achieving efficient synchronous extraction of nickel (Ni), copper (Cu), and cobalt (Co) from low‒nickel matte with sodium sulfate as the sulfating addictive. Under optimal conditions, the recovery efficiency of Ni, Cu, and Co metals can achieve 95%, 99%, and 94%, respectively, whereas the recovery efficiency of Fe metal is less than 1%. The results revealed that the mechanism of the sulfating roasting pretreatment could form a liquidus eutectic compound sulfates [Na2Me(SO4)2] (Me = Ni, Cu, Co) at the solid–solid interface, which plays a significant role in promoting the leaching efficiency of valuable metals. Not only enhance the reaction kinetics of sulfation, but improve the utilization efficiency of SO2/SO3. Thus, the sulfation roasting‒water leaching process developing an efficient and eco-friendly pathway to simultaneous extraction of Ni, Cu, and Co valuable metals from low grade sulfide ores.

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With the development of advanced Internet technology, business applications across multiple enterprises based on Web Services Composition (WSC) paradigm are widely used. When system failure occurs, some tasks of the flow may be committed while others unscheduled, in this situation, it is important to accurately analyze execution log of composition business process. In this paper, we formally defines Web services composition compensation based on paired net, and analyze execution logs, dataflow dependency and behavior dependency between tasks in composition process, and discuss the refinement for Web services composition compensation process and the abstract replacement of complex compensation process. The classical composition transaction application Trip Reservation Process (TRP) shows the feasibility of ensuring consistent execution of reliable composition.