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Flashcards in industrial chemistry Deck (52)
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1

contributions of chemistry to society

1- provides chemicals, pharmaceutical, fuels, medicines, agrochemicals, etc

2- provides materials such as plastics, semi-conductors, synthetic fibres, etc

3- provides stable well paid employment and contributes to knowledge economy

2

james muspratt

nationality: Irish

field: chemist, industrialist

"father of the modern chemical industry"

3

principles of industrial chemistry

batch process
continuous process
semi-continuous process

4

batch process

reactants/feedstock are allowed to react for a fixed time with each other inside a vessel known as a batch reactor, under controlled conditions of temp and pressure. When reaction complete, product is isolated

5

continuous process

feedstock continually fed in at one end of plant + product continually removed at other end. All case studies are continuous

6

semi-continuous process

combination of batch process + continuous process. First stage involves batch process to make product, second stage involves continuous process where product is purified using feed from various batch reactors

7

batch process advantages

-low capital costs
-easier to cater for slow reactions
-versatile (usable for diff processes)
-usable for trial runs
-suit seasonal products

8

batch process disadvantages

-time consuming + labour intensive
-contamination more likely
-difficult to control exothermic reactions

9

continuous process advantages

-low risk of contamination since only one product is being made
-long periods of use w/o stopping for maintenance
-suitable for large scale production
-long periods between maintenance

10

continuous process disadvantages

-high capital costs
-less flexibility as plant is tailor-made for a specific product
-not cost effective unless run at full capacity

11

characteristics of an industrial chemical process

raw materials: limestone from local quarry and seawater from Boyne estuary

feedstock: calcium hydroxide and purified seawater

reactants are called feedstock and produced from raw materials

12

reaction rate

-main reaction is fast
MgCl₂ + Ca(Oh)₂ --> Mg(OH)₂ + CaCl₂

-to slow process down for formation of large crystals, incoming seawater is diluted with spent seawater
-reaction mixture is seeded with Mg(OH)₂. High temp of 900°C speeds up loss of water from MgO

Mg(OH)₂ --> MgO + H₂O

13

products

co-products
by-products
product yield

14

co-products

other products made along with main product - in this case, CaCl₂

15

by-products

products made from side reactions, which reduce yield of main product - no by-products in this case

16

product yeild

2g MgO from a litre of seawater

17

waste disposal and effluent control

-dust removed by electrostatic precipitators
-gases scrubbed to remove SOx + grit
-used seawater contains Ca(OH)₂ which is alkaline + has to be neutralised to reduce pH
-filtered to remove suspended solids before being released back to sea

18

quality control

analysis of all reactants + products are carried out at every stage. Acid-base titrations used + x-ray fluorescence is an instrumentation technique used to test purity of MgO crystals

19

safety

-ongoing health + safety training for staff on site
-personal protective equipment (ppe) - helmets, boots, goggles, ear plugs, clothing

20

costs

fixed costs
variable costs

21

fixed costs

-those that have to paid regardless of rate of production of plant

-labour, plant depreciation, repayment of loans etc.

22

variable costs

-depend directly on rate of production of plant

-costs of raw materials, costs of effluent treatment and disposal, distribution costs, plant maintenance, administration, etc

23

how to reduce costs

recycling + using waste gases for heating

24

site location

-plentiful supply of seawater from Boyne estuary
-site located near local limestone quarry w/ good road + rail network for easy transport
-highly skilled workforce available
-site had suitable equipment already as it was previously a cement factory

25

construction materials

large concrete silos.
kilns and furnaces lined w/ refractory bricks
many buildings made of steel w/ outer cladding
materials that are un-reactive + resist corrosion used

26

case study

Premier Periclase

27

Premier Periclase - manufacture

manufacture of magnesium oxide is carried out by Premier Percilase in Drogheda, Co. Louth

28

Premier Periclase - process

-a continuous process.
-MgO occurs in the mineral periclase. Has high melting point 2800°C + used to make refractory bricks, which are heat resistant for lining furnaces
-MgO powder made into pellets + briquettes

29

Premier Periclase - raw materials

limestone CaCO₃

sea water

30

Premier Periclase - feedstock

calcium hydroxide Ca(OH)₂

purified seawater