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Fine tuning improves efficiency

Summary

Better catalysts, improved process control, simpler design and greater flexibility are key to the latest developments that have been applied to selective catalytic oxidation processes. Lisa Connock reports on Superclaus/Euroclaus, Clinsulf-DO, Selectox and the High-Activity processes.

Abstract

In recent years, dry selective catalytic oxidation processes, which convert H2S directly to sulphur, have undergone a series of improvements as a result of new developments and fine tuning. A summary of the main processes and their most recent developments are given below.

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Meeting the challenge of high-grade SO2

Summary

Outokumpu-Lurgi Metallurgie has developed a new process for processing high-concentration SO2 smelter off-gas without using excessive air dilution. Karl H. Daum discusses current sulphuric acid technology for processing high-grade SO2 with respect to technical boundaries and economic aspects of different process alternatives.

Abstract

At pyrometallurgical smelters based on sulphide ore concentrates of copper, nickel, lead or zinc, it is traditional practice to convert the SO2 off-gas to sulphuric acid. Many cost studies have shown that the production of sulphuric acid remains the most viable option for sulphur recovery from smelter off-gas and abatement of SO2 emissions to the atmosphere.

The growing awareness of environmental protection has led to increasingly stringent regulations, primarily aimed at the reduction of SO2 emissions in defined off-gas streams, such as the tail gas of sulphuric acid plants, which are attached to smelters to act as a desulphurisation system. There is also increasing emphasis on the residual ground level concentration, which requires the control of minor and fugitive emissions within the smelter. Even with improved hooding and draft control, this generally leads to an increase in the total off-gas volume to be treated and a dilution of the concentrated SO2 offgas stream from the smelter.

The operation of modern pyrometallurgical smelter processes for sulphide ores using oxygen-enriched air, leads to high SO2 concentrations in the smelter off gas.This is a prerequisite for substantial savings in smelter off-gas treatment. Consequently, one of the main objectives in process development for metallurgical sulphuric acid plants is to enable operation with very high SO2 concentrations, while simultaneously avoiding the generation of diluted gas from, for example, Pierce Smith converters. Higher grade SO2 gas obviously leads to a reduction in the specific equipment size of the gas handling system, i.e. the gas purification and sulphuric acid plant. In order to realise this benefit, the smelter and converter processes must be fully continuous without any batch operating steps, so that the acid plant can be designed for constant gas conditions.

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Final demand for sulphur

Summary

The International Fertilizer Industry Association's (IFA) recent conference in Philadelphia was an opportunity to see trends in product use by the sulphur industry's leading customers. Current research

Abstract

Suppliers, buyers and traders gathered in their customary huddles around Philadelphia’s Ritz- Carlton hotel at the IFA conference in late May, determining the next half-year’s pricing story for fertilizers including, of course, sulphur. Inside the conference’s sessions, thoughts were less about the impact of shortterm supply/demand scenarios and more about the needs and techniques of the final customer, the farmer.

Nonetheless, topics under discussion – efficiency of fertilizer use, as well as the biggest prize of agribusiness, genetic modification of crops – had the promise to reveal much about future demand for major nutrient supplies.Would GMOs mean less phosphate consumption on farms of the future? That would certainly be tough news for the sulphur trade.

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Setting the standard

Summary

As a supplement to the article "Titania-based Claus catalyst performance", which appeared in issue no. 285 of Sulphur and reported on several titania catalysts that have been introduced to the market in recent years, J.L. Ray and François Chapat of Axens provide some performance results of catalyst CRS 31, the industry standard for titania catalysts, against which the newcomers can be compared.

Abstract

Axens’ CRS 31 catalyst was the founding father of the titania catalyst family and, as the market’s leading premier SRU catalyst, it is the standard against which others are judged. In order to give the reader the opportunity to compare more recent titania catalysts with CRS 31, we report the performance of CRS 31 from pilot results through to the most recent commercial ones.

We have paid considerable attention in establishing test conditions of gas composition, space velocities and temperatures. These data should be made available in all cases to have the best understanding of the results.

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A shifting balance

Summary

Alberta's latest forecasts of future production of sulphur highlight the increasing contribution of oil sands operations to output over the next decade.

Abstract

The story of sulphur production in Alberta over recent years has remained relatively steady. Strong demand for the province’s natural gas has meant no spectacular changes in year-on-year production statistics, although latterly increasing demand from China for Canadian sulphur has seen some reversal of Albertan policy of pouring excess production to block.

Whilst plenty of sulphur is produced from oil sands, that industry’s isolated sulphur extraction operations have meant that little is available to major markets. But changes are afoot in regional plans for upgrading bitumen extracted from oil sands. According to the latest forecast of sulphur production from Alberta’s Energy and Utilities Board (EUB), the next decade will see a rapid increase in the amount of Canadian sulphur on the move.

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