Seminar Report on e Waste Recycling

8/3/2019 Seminar Report on e Waste Recycling

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SEMINAR REPORT ON

Electronics Waste Recycling SUBMITTED IN PARTIAL FULFILLMENT FOR AWARD OF DEGREE OF

MASTERS OF TECHNOLOGY

IN

ELECTRONICS AND COMMUNICATION ENGINEERING

BY

CHETAN MOHAN (Roll No.M-71304164)

UNDER THE GUIDANCE OFDr. Ajay Kumar (Assoc. Prof, ECE)

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERINGBEANT COLLEGE OF ENGINEERING AND TECHNOLOGY, GURDASPUR

November 2011


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INTRODUCTION

This project is an advanced chemicaltechnique to recover precious metal like gold

from thrash.

This is an advanced and economicaltechnique.

Layman should not try it at home. This

requires an expert guidance and hands onknowledge of chemicals.


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Tons of electronics scrap gets generated every year and it is very dangerous to the environment


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So, the first stage of the experiment is to recover all these pins and connectors.We need pliers and cutters, flat and Philips screwdrivers, and liberal amounts of elbow grease...


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We need a lot of pins to conduct this experiment, and that's exactly what we want to do..


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To recover the few micrograms of gold deposited on the pins, we're going to use anelectrolytic cell. The bath consists of a 95% solution of sulfuric acid. The cathode is lead andthe anode is copper. The pins are placed in the copper anode, which we've formed into abasket shape.


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By running an electrical current through the cell, using an ordinary battery charger, the copper in theanode (and in the pins) dissolves and is deposited on the lead cathode. The gold, detached from thecopper, forms a sediment at the bottom of the cell. Also note that the temperature of the bathincreases significantly during this process


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Once all of the gold has detached from the pins, the bath is allowed to settle.Then, we recover as much of the sulfuric acid as possible, before diluting what remains in the bottom

of the electrolytic cell.


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Be careful to always pour acid into water, and not the other way around! If you do it wrong, the firstdrops of water that touch the surface of the sulfuric acid will immediately be vaporized and could causeacid splashes.


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We end up with a diluted solution of sulfuric acid, various metals (including gold), and waste thatthen needs to be filtered. Why not just filter the solution directly, without diluting it? Because paperfilters don't stand up well to strongly concentrated sulfuric acid. That's why.


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What remains in the filter is a mixture of various metals and impurities. We now dissolve everything ina mixture of hydrochloric acid at 35% and chlorine bleach (sodium hypochlorite) at 5%, in a proportionof 2 to 1.2 HCl + NaClO -> Cl2 + NaCl + H2O

C f l h i i hi hl h i d d hl i hi hl d Chl i


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Careful! The reaction is highly exothermic and produces chlorine, a highly dangerous gas. Chlorinegas was used as a chemical weapon during the first World War, under the name bertholite.

I f h hl i d d b i i h d hl i id d hl i bl h i h ill di l h ld


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In fact, the chlorine produced by mixing hydrochloric acid and chlorine bleach is what will dissolve the gold toform gold(III) chloride. 2 Au + 3 Cl2 -> 2 AuCl3

N ll d d i fil hi i


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Now, all we need to do is filter everything once again.The filter will retain all the impurities, leaving only a gold(III) chloride solution.

T th t lli ld d t i it t th ld th t i l ti


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To recover the metallic gold, we now need to precipitate the gold thats in solution.For that, we use powdered sodium metabisulfite.

In the presence of water, the sodium metabisulfite produces sodium bisulfite.

Na2S2O5 + H2O --> 2 NaHSO3 This sodium bisulfite is what will allow the gold to precipitate.

3 NaHSO3 + 2 AuCl3 + 3 H2O --> 3 NaHSO4 + 6 HCl + 2 Au

Now all we need to do is to melt the powder in a crucible


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Now, all we need to do is to melt the powder in a crucible. The melting point of gold is around 1064 C (1947.52 F), so an oxy-butane torch will do the job.


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And here's the result!


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Pure 24K gold is now with us.


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QUERYs Please .?


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THANK YOU

Seminar Report on e Waste Recycling

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