BC Insight - Nitrogen+Syngas, Sulphur, Fertilizer International
Login
BCInsight Ltd
China Works
Black Prince Road
London, SE1 7SJ
United Kingdom
Tel: +44 (0)20 7793 2567
Fax: +44 (0)20 7793 2577

Publication > Issue > Articles

Chinese demand is more refined

Summary

Chinese imports of brimstone from main suppliers Canada and Japan have burgeoned in recent years. Chris Cunningham reviews how China's widening oil debit may drive up competition for imports from home produced sulphur.

Abstract

With the Chinese economy ­apparently sailing blithely through a sea of economic turmoil in its region, the inward prospects for exporters of all shades look pretty good. But it may be a little early to bank on China staying free of the rocks.

The Chinese market for brimstone imports has developed from being a major new opportunity to becoming a key vector for global prices, in seemingly no time. And as the economy has progressed, not just the size but the shape too of sulphur trade in the country has developed.

China’s growing imbalance in oil supplies means that major new resources of recovered refinery sulphur could soon be on the scene. As a result, sulphur burning should continue to chip away at more established resources of sulphuric acid in China – pyrites roasting and smelter acid. But there is a strong likelihood that two competing streams of supply will develop.

How quickly each of these streams runs will depend on the Chinese economy. In the first quarter of 1999, Chinese growth was at an annualised rate of 8.3 per cent and Beijing continued to insist that the Renminbi would not be devalued. At the same time, exports were down for the first time in 15 years, and inward investment, the lifeblood of China’s potential for oil refining, was in decline. Most of the recent growth is down to state-funded schemes.

Add to basket


An exception to the rule

Summary

Despite the advantages of natural gas as a fuel, coal continues to be an important energy source in many countries. In this article, Petr Buryan and Josef Vejvoda of the Institute of Chemical Technology, Faculty of Environmental Technology, Prague, report on a cogeneration plant in Vresová, Czech Republic which produces sulphuric acid from desulphurization offgases.

Abstract

In the Czech Republic, electricity is generated predominantly by the combustion of pulverised coal. To comply with environmental regulations, power plants are retrofitted with flue gas desulphurization pro­cesses, the most widespread technology being wet limestone scrubbing which produces gypsum.1-3 Almost all power plants use brown coal from local deposits.

Sokolovská uhelná Utilities’ power plant at Vresová is an exception. It produces electricity from brown coal using integrated steam-gas cycle technology. Formerly a gasworks producing town gas using the Lurgi pressurized moving bed gasifier process, the facility has now been converted to a power plant for the production of electricity and heat for surrounding towns and villages. The gasworks was constructed according to the know­how of Energoprojekt Prague and now covers two units with installed capacity of 185 MWe using Alsthom/General Electric combustion turbines which are fed by gas from Lurgi generators.

The units are used for the production of electricity in semi-peak or peak load regimes. They started operating at full scale production in 1993 and by 1998 had clocked up more than 30,000 hours of power generation. The power plant can be put into operation from cold and reach full operating capacity in 8 minutes.

Add to basket


Maximizing energy ­savings in sulphuric acid plants

Summary

Since the late 1980s, the highly exothermic sulphuric acid manufacturing process has been an ever increasing net exporter of energy. As energy prices have risen, the role of the modern sulphuric acid plant as a thermal power station has taken on increasing importance. Lisa Connock reports on Monsanto's and Lurgi's latest heat recovery systems for sulphuric acid plants.

Abstract

Since the 1980s leading sulphuric acid plant designers such as Mon­santo Enviro-Chem Systems in the USA and Lurgi Metallurgie in Germany have introduced several new technologies for improved heat recovery in new and existing sulphuric acid plants.

When retrofitting sulphuric acid plants for maximum energy savings, each plant must be evaluated based on its existing equipment and value of power to determine the best selection of energy recovery options.

Add to basket


A new generation of pressure leach projects

Summary

The pressure acid leach process which uses significant volumes of sulphuric acid to extract nickel and cobalt from laterite ore is expected to have a big impact on the world nickel market over the next decade. Lisa Connock reports on the Cawse, Bulong and Murrin Murrin projects in Western Australia.

Abstract

Three major new pressure acid leach (PAL) nickel laterite projects with a combined capital cost of about AUS$ 1.625 billion have recently started up or are in the final stages of commissioning in Western Australia (Fig. 1). When operating at full scale capacity these projects will consume in total approximately 1.95 million t/a of sulphuric acid in the first few years and potentially much more if planned expansions go ahead. Several more laterite projects are also planned elsewhere.

Historically, nickel has been extracted from its ore by smelting (pyro­metallurgical route) or by reduction roast/ammonia leach processes (a mixed pyrometallurgical/hydrometallurgical route known as the Caron process). The sole exception is Moa Bay in Cuba which has been using a hydrometallurgical pressure acid leach process for some 40 years.

The PAL process involves the use of sulphuric acid to leach ore slurry at a temperature of about 250°C and pressures of around 4000 kPa for between 80 and 120 minutes in a titanium clad autoclave. Various refining steps follow to remove the impurities.

In the case of nickel laterite ores where the nickel is a component of a silicate lattice, pressure acid leaching is the most suitable processing route available.

The sudden popularity of pressure acid leaching after so many years of scepticism about the technology can be attributed to five key driving forces:

  • Capital costs are much lower than the Caron process.
  • All three projects are aiming to pro­duce nickel at cash operating costs within the lowest quartile of world production.
  • The PAL route offers higher metallurgical recoveries and lower energy requirements than the Caron pro­cess. For example, nickel and cobalt recoveries for the Cawse PAL nickel project are expected to be greater than 95%, compared to 75% for nickel and 40% for cobalt using the Caron process.
  • Technical advances over the last ten years, which include better auto­clave technology and better refining techniques, e.g. solvent extraction/electrowinning (SX-EW) and the use of extractants.
  • Cheap sources of acid and/or sulphur used to make acid for the PAL process. (Environmental pressure has forced smelters to find markets for its waste sulphur or sulphuric acid.)
  • The availability of relatively low cost energy.

Besides the all-important selling price of nickel and cobalt and tax issues, the two major variables that can affect the economic viability of the acid leach process are:

  • the consumption of acid by the leach process; and
  • the energy requirements, in particular the quantity of steam required to heat the ore and accompanying water to the process temperature.

 

Add to basket


Copper bottomed ­uncertainty

Summary

Since Zambian copper's last heyday, production technologies and environmental requirements have made a big impact on the smelting industry. Chris Cunningham surveys the key role that trade in sulphuric acid will play as the Copperbelt stages a privatised comeback.

Abstract

Once the pride of newly-independent Zambia,the country’s copper industry has taken a mighty fall. From an output of 700,000 t/y at the start of the 1970s, production of copper from the Zambian Copper­belt region has fallen to some 300,000 t/y.

The government’s plans for renewal have involved the sale of the industry as a series of lots from the single ownership of state-run Zam­bian Consolidated Copper Mines (ZCCM).

A continuing round of investment sales has dispersed control of the region’s mining interests, rich in high grade copper sulphide and oxide ores but ranging in productivity from old, complex workings to the massive potential of the Konkola Deep Mining Project. Along with the mines go huge tailings and waste dumps – historically, limited levels of ore concentration means that the dumps also are relatively rich in copper and cobalt – as well as ore concentrating plant, concentrate smelters, and solvent extraction/electrowinning (SX/EW) installations. The sale has drawn some of the biggest names in the world’s mining industry, chiefly from South Africa and North America, but also from Chinese and Japanese interests looking to ensure their own supplies of smelter concentrate.

Add to basket