Year 12 Chemistry: Chapter 18~ The Chemical Industry: Risks and Rewards
18.1 Australia’s Chemical Industry
Demand for rubber, plastics and packaging drives Melbourne’s chemical industry today.
A range of different skills and qualifications are required by industrial chemists. Chemical engineers: operation and design Analytical chemists: quality control Research chemists: development of new analytical techniques.
18.2 A Global Enterprise Chemical industries convert raw materials, such as plant material. Minerals or atmospheric gases, into useful and profitable products.
Example: Sodium hydroxide Manufacturing soap, detergents, cosmetics, pharmaceuticals, bleaches, paper, rayon, cellophane, dyes and cleaning compounds. Refining vegetable oil and petroleum Engraving and etching Peeling fruit and vegetables Electroplating
18.3 Inside a Chemical Industry A chemical industry must operate efficiently if it is to make and market a product that will provide company shareholders with an adequate return on their investment. At the same time, companies must operate in a responsible manner that minimises hazards to employees and damage to the environment. The needs to be efficient and to be environmentally responsible are often conflicting.
It is important to build a plant that produces the maximum amount of product at the lowest possible cost. Yields The extent and rate of conversion of raw materials to products is influenced by reaction conditions such as temperature, pressure and concentration. To avoid waste and reduce costs, conditions are carefully selected to ensure that acceptable yields of product are obtained. The reaction rate is fast A high proportion of reactants is converted to products at equilibrium There is often a need to compromise between rate and equilibrium considerations.
Conditions that favour fast reaction rates and high equilibrium yields For Fast Rates
For High Equilibrium Yields
Batch and continuous processing Back Processing Batch processing is the method used when fixed amounts of reactants are mixed, giving fixed amounts of products. Continuous flow Processing In continuous flow processing, reactants are mixed continuously, providing a constant supply of products. Continuous flow processing allows greater control over reaction conditions.
Costs Expense, may influence the selection of: Catalyst Pressure (high pressure vessels are costly) Temperature (fuel costs rise with increasing temperature) Choice of reactant to use in excess Safety and waste minimisation and disposal
Energy Costs are associated with energy use are closely monitored. Energy use can sometimes be reached by careful choice of processes.
With efficient management, heat produced in one part of a plant may be utilised elsewhere. If sufficient thermal energy is generated, it may be possible to convert it to electrical energy for use in the plant and perhaps, sale to the electricity grid supply grid.
Questions: 3, 5, 7, 20. Year 12 Chemistry: Chapter 18.4 Working Safe and Green Chemistry
18.4 Working Safely Occupational Health and Safety (OH&S) Australia has laws that enforce a duty of care by organistions that supply or use chemicals. Chemical industries also self-regulate their activities. There are six codes covering all aspects of the life cycle of the chemical: Community right to know Manufacturing process safety Environment protection Storage and transport safely Employee health and safety Product stewardship
Dangerous Goods and hazardous substance Dangerous goods have the potential to pose immediate danger to people, property or the environment. The risk typically arises during transport, storage or handling.
Dangerous goods are assigned a specific United Nations (UN) identity number and classified as: Class 1: Explosive Class 2: Gases (flammable, non-flammable, toxic) Class 3: Flammable liquids Class 4: Flammable solids (spontaneously combustible or emit flammable gases when wet) Class 5: Oxidising Class 6: Toxic or infectious Class 7: Radioactive Class 8: Corrosive Class 9: Miscellaneous dangerous substance *Check out Prep room Hazardous substances are classified on the basis of their short- and long- term effects on the health or safety of people, typically in the workplace. Over 2000 Australians die each year as a result of exposure to hazardous substances.
Warning signs about dangerous goods are required at any site where they are used or stored.
Material Safety Data Sheets (MSDS) and Risk Assessment A risk assessment is a formal way of identifying risks and assessing potential harm from a hazardous chemical in a particular situation. Effective risk management reduces exposure to hazardous chemicals to at least acceptable levels.
Victoria’s Occupational Health and Safety (Hazardous Substances) Regulations 1999 require all work places, including schools, to perform a risk assessment for each activity using hazardous chemicals. A risk assessment should include the following steps: 1. Identification of hazardous chemicals 2. Assessment of the risk (use MSDS) 3. Control of the risk 4. Documentation (risk assessments last for 5 years) Legislation requires manufacturers to supply Material Safety Data Sheets (MSDS) for hazardous substances. An MSDS provides detailed information: Company name Scientific and trade names Major uses Physical data Health effects Treatment Precautions for use Safe handling Data of publication: MSDS must be less than 5 years old.
18.5 Waste Management and Pollution Bioaccumulative: the tendency of a substance to increase in concentration as it moves through a food chain. Waste: unwanted or unvalued substance that is discarded or discharged. Hazardous waste: may be toxic, radioactive or contaminated by disease-causing organisms.
Chemical waste is generated from many sources, including corrosives, acids and bases, solvents and flammable materials, heavy metals, poisons, pesticides, fertilisers, explosives, and productions of combustion. The waste can be in solid, liquid or gaseous form. Some chemical waste may not pose any hazard, but other may cause subtle damage that appears only after long-term exposure. Some benzene is emitted from cars running on unleaded petrol. Polychlorinate biphenylis (PCBs) and dioxins and DDT are persistent (they have long half lives and take a long time to break down). They are also bioaccumulative, being retained in body tissues and resulting in increases concentrations as they move through the food chain.
Governments, industry and the general community all have roles and responsibilities in waste management.
The 2002 World Summit on Sustainable Development set a target date of 2020 for ensuring that chemicals are used and produced in ways that minimise significant adverse effects on human health and the environment. Globally Harmonised System (GHS) is a common system for describing chemical hazards and information has been in use in Australia since 2006.
Ideally, chemical waste management should be part of a sound follow the principles of green chemistry to minimise or eliminate hazardous substances. The EPA and local governments regulate waste disposal.
Waste Treatment High temperature incineration (over 1100C) Vitrification (sealing of slag) Dispersion in controlled amounts in water or air Removal of pollutants from waste gases and liquids Storage in sealed drums in secure locations Catalysed dechlorination Ionic replacement of halogens in halogenated organic compounds High-temperature steam and water treatments. Chemical waste management needs to consider: Quantity Physical form Threats to people and the environment Economically, socially and environmentally acceptable options for disposal.
Chemical industries aim to deal with wastes in the following strategic order of priority: 1. Prevention 2. Elimination 3. Reduction 4. Recycling 5. Treatment 6. Disposal Waste management also applies in the school laboratory.
Green Chemistry 18.6 Community Safety Accidents: 1984: Bhopal, India. 2500 people died 1976: Seveso, Italy. 37 000 people exposed to the chemical. Responsible companies recognise and accept their obligation to provide a working environment for their employees and nearby residents that is as free of hazard as possible.
18.7 Location of a Plant Factors considered in locating a plant: Availability of raw material
Proximity to markets
Proximity to other, interacting, chemical manufacturers
Transport cost
Availability and cost of energy
Labour supply
Environmental concerns
Waste disposal facilities
Water supply
Legal, social and political constraints
Cost of land
Questions: 9, 11, 12, 13, 15, 17, 27, 28