Acido Sulfurico

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Mechanical Integrity Best Practice for Sulphuric Acid Plants
Michael Robert Beaumont Assistant Vice President, Group Manager Field Engineering FM Global - Australian Operations Level 15, 255 George Street, Sydney, NSW 2000 Australia Phone: +61 2 8273 1421 michael.beaumont@fmglobal.com © 2006 Factory MutualInsurance Company. All Rights Reserved.

Abstract
In applying the principles of process safety management to a sulphuric acid plant, Process and Equipment (Mechanical) Integrity is one of the most important elements. The harsh operating environments that exist throughout an acid plant result in the need for careful attention especially to reliability engineering, materials selection, goodoperating principals and especially good maintenance regimes. Extensive downtime for sulphuric acid plants is really not an option for any company operating one. In most pyrometallurgical smelter complexes, loss of the acid plant would immediately necessitate shut down of the entire plant due to pollution concerns. Where acid is used as a raw material (e.g., fertiliser industry, hydrometallurgicalmetals production) or regenerated in the chemical process industry, the interruption of raw materials would have an immediate effect on downstream processes. Of particular note, in the metallurgical processing industry, there is a noticeable shift from acid producers (pyrometallurgical processes) to acid users (hydrometallurgical processes). This is resulting in a reduction of available and relativelycheap smelter acid. In turn there has been a large increase the value of sulphuric acid. Because of the issues noted, the drive to improve plant availability and avert catastrophes that could result in long term plant outage is of paramount importance to the industry. Although some industries (such as the Florida fertiliser industry) have gone a long way to developing best practice, there is aneed to consolidate these best practices across all industries, especially new hydrometallurgical plant operators now operating large sulphur burning plants. This paper looks at some best practice maintenance and operating procedures for sulphuric acid plants within the scope of mechanical integrity. More specifically, it breaks down the analysis of the plant into six key elements: Environment,Operating Conditions, Age/History, Maintenance, Operators, Safety Devices, and Contingency Planning. The overall goal is to open up a discussion on best practice for the industry.

1. Introduction
Sulphuric acid is an extremely important industrial chemical, probably one of the most important in the world. Currently, about 37.9 million tonnes of sulphuric acid is produced worldwide. It is

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used to manufacture a wide variety of other chemicals from fertilizers to pharmaceuticals. It is also used in a variety of important production processes from impurity removal to metal ore leaching. Approximately 70% of the sulphuric acid used is for the manufacture of fertilisers. Most of this acid is produced bysulphur burning plants on-site. The next most important producer would be metallurgical smelters, whose production ranges between 10-15% worldwide. Although demand for sulphuric acid had only been increasing at a rate of about 1% per year in the USA over the past several decades, the rate is now close to 10% and international figures are similar. Subsequently, the price of acid has been driven upsubstantially (40% in 2004) and the high price and demand appears to be increasing with further rises likely (but more likely on the 10% level). This appears to be especially true with the apparent rise in demand in China. The fertiliser industries in Florida, the traditional major consumers, have been expanding their own on-site capacity to make up for a decrease in the supply of both smelter...