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

The market for low density AN

Summary

Although a minority use for ammonium nitrate, the explosives sector continues to provide one of the major growth areas for the compound.

Abstract

While ammonium nitrate’s future as a fertilizer is beginning to look more doubtful, with progressive bans in China, Algeria, Colombia and the Philippines and a steady tightening of regulations worldwide, as an explosive it has never been more popular. Indeed, ammonium nitrate remains the most popular commercial explosive in the world, widely used in mining and quarrying.

Add to basket


Filamentary filters in AN-NA applications

Summary

Some of the range of products designed to separate particles from fluids are used to great advantage in ammonium nitrate and nitric acid plants.

Abstract

Filters comprising knitted or woven wire or monofilaments of a range of durable materials are widely used in industrial applications for arresting particles which have be­come aspirated in gas streams. In general, the finer and more efficient this kind of filter is the less suitable it is for removing solids because it is more susceptible to blockage, but it is eminently well suited to arresting liquid spray droplets as long as the liquid formed by coalescence of the captured droplets can drain away free­ly. Liquid spray is almost bound to be formed in any gas-liquid contact device or any vessel in which gas or vapour is evolved from a boiling or frothing liquid (boilers, evaporators, desulphurisers and other gas washing columns, strippers, and distillation columns, to name but a few).

The reasons for wanting to arrest aspirated droplets depend on their nature and the location in the plant where they are formed. Acidic droplets are likely to damage metallic surfaces, while any kind of liquid can damage catalysts operating at high temperatures by thermal shock or fouling (or both). Sprays emitted into the atmosphere may be a health or environmental risk. Mesh filters provide a reasonably-priced, durable, effective method of arresting spray with no moving parts and without imposing too much in the way of a pressure drop penalty.

Add to basket


Retrofitting nitric acid and ammonium nitrate plants

Summary

Though no fundamentally radical changes have taken place in nitric acid and ammonium nitrate technology in the past decade, there are still many older plants which could benefit from retrofitting to bring them up to modern standards of efficiency and cleanliness.

Abstract

A decade or so ago nitric acid and ammonium nitrate production technologies had attained such a degree of maturity that there would today be little to gain by replacing a plant of that vintage with a completely new one. But there are still plants from older generations in use which do not have the benefit of the latest technology and now face extinction either on account of their economics or because they no longer meet the applicable environmental standards. Some of these, though, have been so overtaken by circumstances that they have little or no prospect of being replaced with new plant, anyway: the end of their useful life signals the end of the enterprise. That could be because of high feedstock prices or because of unfavourable developments on the market for the product. Another factor that has become more significant in the past three years is uncertainty about the long-term future of ammonium nitrate as a fertiliser. For such cases, revamping is a potentially attractive proposition as a means of extending the useful life of the plant at a small fraction of the cost of building a new one.

Add to basket


Advancements in methanol catalysts

Summary

Norbert Ringer of Sud-Chemie discusses the development of a new methanol synthesis catalyst for Lurgi's MegaMethanol process.

Abstract

n the 1920s, methanol was produced on an industrial scale over a catalyst that consisted of zinc and chrome oxide. This catalyst re­quired a reaction temperature of 350°C and higher because of its relatively low activity compared to today’s standards. Figure 1 shows an equilibrium chart with methanol concentration as a function of temperature and pressure for a typical synthesis gas composition, and as can be seen, a relatively high pressure of 300 bars is needed to get reasonable conversion at these temperatures. This pro­cess is became known as the high-pressure meth­anol synthesis process.

Since the 1920s much effort has been put into catalyst research. This effort has led to the development of more active copper-zinc based meth­anol synthesis catalysts, which allow­ed operation at temperatures of 250°C and below. With those catalysts it was possible to re­duce the methanol synthesis loop pressure to 60-80 bar and even low­er, resulting in the low-pressure meth­anol pro­cess. In fact, Sasol Chem­­icals in Sasolburg, South Africa operates a small methanol loop at a pressure of not more than 40 bars. The reactor was originally a Fischer-Tropsch synthesis converter, revam­ped to produce methanol. Indeed, Süd-Chemie has conducted bench-scale tests with its C79 series of methanol synthesis catalysts at operating pressures as low as 20 bar. The tested catalysts still provided excellent conversion rates at these low pressures.

Add to basket


Non-fertilizer uses of nitric acid

Summary

Nitric acid is one of the basic chemical building blocks of the nitrogenous fertilizer industry, used in ammonium nitrate and nitrogen solutions as well as various NPK compounds. However, it is also a feedstock for a number of other chemical processes.

Abstract

Nitric acid is mostly produced as ‘weak acid’ (50-65% by weight), for use in ammonium nitrate production as well as adipic acid manufacture. Higher concentration nitric acid is used for some specialist applications like metallurgy, and is generally produced by concentrating weak acid rather than by producing it directly.

Production of weak nitric acid uses the Oswald process, which has three main stages; catalytic oxidation of ammonia with air into nitric oxide (NO); oxidation of nitric oxide into nitrogen dioxide (NO2); and absorption of nitrogen dioxide into water to produce nitric acid. Liquid ammonia is filtered and vaporised before injection in the catalytic converter. Filtered and com­pressed air is added to obtain an ammonia-air ratio of 1:10 in order to stay below explosion limits. Most of the ammonia is converted to nitrogen oxide using a platinum gauze catalyst, often reinforced with rhodium, at 800-900C. The ni­trous gases are then cooled to prevent further oxidation to nitrogen dioxide. As this reaction is also exo­thermic, continuous cooling is re­quired. Absorption of nitrogen dioxide in water is performed at high pressure, up to 13bar.

Add to basket


A balanced portfolio

Summary

As one of Europe's main fertiliser producers, Grande Paroisse has built up a substantial portfolio of well-proved technology, which is available for licence.

Abstract

France’s main fertiliser producer, Grande Paroisse SA (GP), is a major manufacturer of ammonium nitrate, urea and phosphates, and over the years it has built up a portfolio of interesting process technologies relating particularly to nitric acid and ammonium nitrate production and to compound fertilisers based on both ammonium nitrate and urea. These technologies are offered for licence.

GP was founded (as Société Chimique de la Grande Paroisse) in 1919 in the municipality of Grande Paroisse, Seine et Marne, to produce ammonia and nitrates. It was originally a joint venture of Air Liquide and Saint Gobain and remained a subsidiary of Air Liquide until 1987, when, as part of yet another in a succession of restructurings of the French chemical industries, it became associated with CdF Chimie AZF. In another reorganisation in 1990 all the fertiliser manufacturing activities of the Elf Atochem group were consolidated within GP, along with the ownership of the fertiliser technology developed by the antecedent companies.

Add to basket