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It is the process of recovery of silver / i.e . reclamation ofsilver after it has been used for its intended photographic

purpose .

There are 2 main source for silver recovery in radiology .

Used fixer solnDiscarded scrap films

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Silver, one of the precious and noble metals, is used in large

quantities for many purposes, particularly in the in radiographic and

photographic industry. It has been reported that 25% of the world'ssilver needs are supplied by recycling and that 75% of this is

obtained from photographic waste. For this reason, the methods

applied to recover silver from photographic waste are important in

reducing cost and time, and have a positive efect on environmental

pollution.

Need of S.R.

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P=prophit =as silver is precious material than itwill give us prophit.

E=Economic =the money received from the

recovery can be utilized in the for other purpose . A = antipolution=it decreases the heavy metal

biomagnification.

C = conservation =natural resources conservation

E = Efficiency can be increased.

So ultimate goal of all the work is PEACE.

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When the conc. Of the silver in the exceed fromthe 5-6mg/lit. is recoverable .conc. Measuredby the silver estimating papers.

Factors affecting the silver content . Types of films :-double coated < single coated

Orthochromatic gives more silver in fixerthan monochromatic film

Repleshment rate :-higher the rate lower thesilver in fixer

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Electrolysis

Metallic replacement

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When a controlled electrical current is passed

between two electrodes, nearly pure silver

plates out on negatively charged electrode

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Silver Recovery MethodsElectrolytic MethodAdvantages Yields silver with a high

degree of purity Permits reuse of fixer in some

processorsWhen incorporated with a

continuous circulating system

more silver is available forrecovery

Less silver is carried intofollowing wash

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Disadvantages

Capital expenditure can run $150to $15,000

Electrical as well as plumbingconnections are required

A reduction in silverconcentration to 500 mg/L in asingle pass may be the best thatcan be achieved

Requires frequent monitoring formaximum efficiencyNot suitable for silver recovery

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The silver-laden fixerflows into a plastic

bucket or metal barrelcontaining steel woolWhen the silverthiosulfate comes incontact with the steelwool, metallic silverprecipitates out as it isdisplaced by the irongoing into solution.

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Advantages Initial capital expenditure is approximately $30 to $50

Installation is easy, requiring only a simple plumbing connection Can reduce silver concentration to less than 1 mg/L in a single pass Requires little monitoring & uses simple analytical procedures Can be used for silver recovery from wash water

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Disadvantages Yields silver sludge that varies in silver

content, resulting in higher shipping & refining costs Does not permit fixer reuse Cannot be used in a continuous circulating system

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Silver recovered from scrap film Burning method film burned & silver extracted from ash Chemical method proteolytic enzymes in warm water sodium hypochlorite warm/hot solutions of caustic soda or sodium carbonate

Unprocessed - yield about 35 Troy oz./100 lbs. scrap Processed - yield about 16 Troy oz./100 lbs. scrap

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