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New sulphuric acid process from China

Summary

A new concept for sulphuric acid production using pure oxygen, instead of air, and gas recycle to substantially cut emissions of SOx and NOx is being developed in China.* In contrast to the traditional air-blown process, a three-stage conversion/absorption system is used. The process concept has been verified by extensive simulation and calculation. The next stage will be pilot testing and industrial trials to test the process on a larger scale.

Abstract

Sulphuric acid is one of the most important inorganic chemicals and is widely used in phosphate processing, petrochemicals production, mining and many other industries. In 2008, the world production of sulphuric acid was estimated to have totalled 205-207 million tonnes, and sulphur-based production contributes to 63.7% of the total yield1.

Commercial processes for sulphuric acid production use air as oxidant to convert sulphur to sulphur dioxide (SO2) in a furnace, and then to convert the SO2 to sulphur trioxide (SO3) over vanadium catalyst. Because of the limited oxygen concentration of air and its substantial nitrogen content, significant amounts of sulphur oxides (SOx) and nitrogen oxides (NOx) are emitted into atmosphere in the large volume of tail gas, causing pollution which has many social, environmental and legal implications2,3.

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ASRL REVIEW

Summary

A twice yearly review contributed by Alberta Sulphur Research Ltd

Abstract

Storage of solid sulphur: a synopsis of ASRL pilot studies by Peter Clark, Technical Manager, Alberta Sulphur Research Ltd. and Professor of Chemistry, University of Calgary.

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Carbon capture and storage

Summary

It is widely accepted that Carbon Capture and Storage (CCS) is necessary to achieve targeted reductions in greenhouse gases. Mahin Rameshni of WorleyParsons provides an overview of CCS including the current status of innovative flue gas scrubbing technologies and discusses the contribution of sulphur recovery facilities to GHG emissions.

Abstract

Fossil fuel combustion supplies more than 85% of energy for industrial activities. It is the main source of greenhouse gases (GHG) in the form of CO2 and is expected to remain virtually unchanged over the next 25 years as world energy consumption doubles. Coal, which has the highest carbon footprint per unit of energy, accounts for roughly 25% of the world energy supply and 40% of the carbon emissions.

Most agree therefore that Carbon Capture and Storage (CCS), also known as sequestration, is necessary for meaningful GHG reduction in the immediate future. The generally accepted, and likely optimistic, goal is to limit the global temperature increase to 2°C above pre-industrial levels by 21001, which the Intergovernmental Panel on Climate Change (IPCC) has estimated would require a 50-85% emission reduction from present levels by 2050, with emissions peaking no later than 2015.

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Advances in dust control

Summary

Escape velocity curves are a valuable and useful tool to predict dust suppressant performance and behaviour. At Sulphur 2009, Glenn Weagle of IPAC Chemicals described experiments that have been carried out on sulphur dust samples and discussed the findings. It was found that some suppressants can wet a hydrophobic substrate like sulphur in less than one second while others can take minutes to hours. The dust from different commercially formed elemental sulphur products can have different characteristics which may require dust suppressant adjustment.

Abstract

Dust control by chemical suppressants has been used for many years. The simplest and most common dust suppressant is water. Water is usually readily available and inexpensive. However, water is ineffective on substrates that are very hydrophobic like sulphur. Surfactants have been used to modify the water-substrate interface properties to improve the wetting effectiveness on hydrophobic substrates with some success. Keeping a residual effect after the water had evaporated still remains an issue since many of the surfactants are solids when dry. Also many of the highly active wetting agent type surfactants are expensive and can have significant toxicity. This limits their use as a dust suppressant

Recent technological developments have permitted improvements of these aqueous surfactant suppressants. Introduction of charge neutralisation and tackifiers has enhanced the performance of some suppressants. To evaluate and measure the performance of suppressants, ex­perimental methods are required that account for the dust characteristics and interaction with the suppressant. Without careful planned application the dust suppressant performance can be very disappointing and in some cases a complete failure (Fig. 1). Understanding the dust characteristics and interaction with the suppressant is essential. This article will address a number of these issues and concerns and demonstrate that efficient and effective chemical dust suppressant of sulphur dust is achievable and possible.

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Fertilizer demand for sulphur

Summary

Agriculture remains the major use for sulphuric acid, but where are fertilizer markets heading after the economic downturn?

Abstract

Phosphoric acid production – most of it (93%) for fertilizer or other agricultural (feed phosphate) use – represented about 57% of global sulphuric acid consumption in 2008, and ammonium sulphate, again most of it for agricultural use, took another 8% of global sulphuric acid. The global fertilizer market is thus of prime importance to the sulphur industry as a source of demand.

However, 2008 saw some of the weakest demand for phosphates in some time. Phosphate nutrient consumption fell by 7.5% compared to 2007, according to the International Fertilizer Industry Association (IFA). Record high prices for phosphate fertilizers during 2007-8 led to widespread demand destruction. While plants are extremely sensitive to nitrate levels in soil, farmers often believe that they can ‘get away’ with a lower application of phosphates or potash in one year, and consequently might wait a year before returning to normal levels of application. Nevertheless, even during 2009 consumption did not rebound quickly, and global consumption is not expected to exceed the 2007/8 growing season figure until 2010-11.

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Achieving lower SO2 emissions from acid plants

Summary

A wide range of technical solutions to meet stringent requirements from sulphuric acid plants is available. They include caesium-promoted catalysts, scrubbing technologies and modified process configurations.

Abstract

Stronger regulatory requirements regarding SO2 emissions from sulphuric acid plants are an increasing challenge for the industry. During the last years considerable improvements have been made, but with increasing requirements for lower SO2 emissions, the effort to achieve this goal is resulting in more complex technical solutions.

In countries of the European Union, SO2 conversion rates of 99.8% for double absorption plants are statutory. Exact control of the inlet temperatures to the single passes of the adiabatic converter and an appropriate catalyst configuration are key factors in order to achieve constantly high SO2 conversion rates. Sulphur burning sulphuric acid plants can usually achieve this requirement by applying 4-bed converters in a 3+1 configuration or 5-bed converters in a 3+2 configuration. Depending on process design and catalyst configuration, SO2 conversion rates of ≥ 99.9% can be realised. Figure 1 shows the influence of the conversion rate and the inlet SO2 concentration on the specific SO2 emission in the clean gas discharged to the atmosphere.

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Developments in nickel ore leaching

Summary

High pressure sulphuric acid leaching of nickel has proved problematical to implement in practise. However, heap leaching has promised to lower costs for some ores going forward.

Abstract

Nickel is an important metal, widely used in the production of stainless steel. It is also used as an anti-corrosive coating and in various ‘super alloys’ with high temperature and/or pressure resistance, as well as a colorant in glass (to give it a green colour) and a variety of other uses in non-ferrous alloys. It is an abundant metal in the earth – much of the Earth’s core is made from nickel, which being magnetic helps to give the planet its protective magnetic field. Within the crust, it is present in two major types of ores; sulphides and laterites.

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New sulphuric acid producing plants

Summary

From sulphur burning to smelter gas capture, Sulphur's annual survey covers recent and planned construction projects for sulphuric acid production.

Abstract

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