电镀产品上电镀金精确计算产品上金含量分析方法

Gravimetric analysis for different Au solutions

重量分析方法计算电镀金用量

1.0 Purpose

1.1 The purpose of this document is to describe the gravimetric methods to analyze different Au

solutions including Acid Au bath, Aqua regia refining Au solution & Cyanide stripping Au refining solution etc. It’s not recommended to use gravimetric method if Au concentration is less than 0.5g/L.

2.0 Associated Procedures & Materials

2.1MSDS of H2SO4, HNO3, HCl, Na2SO3, PGC & Pd salt

3.0Jig and Fixture Used

3.1 N.A

4.0 S afety Requirements

4.1 Follow Area Safety Rules

4.2Goggles

4.3Safety shoes

4.4Rubber Gloves & disposal plastic gloves

4.5 Chemical Resistant Uniform,

4.6 Chemical resistance apron

5.0Equipment

5.1Fume ‘ cupboard ‘

5.225ml transfer pipette

5.3Gooch Crucible

5.4500ml Conical flask, 250ml, 500ml & 1 liter beaker with watch glass

5.5High temperature furnace.(900 ºC)

5.6Normal oven up to 250°

5.7100ml measuring cylinder

5.8Hot Plate(2~3kw)

5.9Ashless filter paper

5.10Funnel

5.11Desiccator

5.12Balance, accuracy is 0.0001gram

6.0 R eagent

6.1 Sulfuric acid (98%)

6.2 Nitric acid (>65%)

6.3 HCl concentrated & HCl(50v/v%);

Address：16 Collyer Quay, #26-01 Income@Raffles, Singapore 049318 Tel:+ 65-6589 8045 Fax:+65- 6589 8041

6.4 Sodium sulfite, anhydrous, Na2SO3

6.5 Aqua regia (HNO3:HCl=1:3)

7.0 C leanliness

7.1 All beakers & volumetric flask used for analysis must be carefully cleaned with D.I. water

before being used.

8. Procedure

8.1. Procedure for citric acid Au bath & cyanide stripping refining solution

8.1.0 Clean crucible with Aqua Regia & thoroughly wash with DI water,

and then dry up in 110°C clean oven for 2 hrs. Store clean & dried

crucible in desiccator.

8.1.1. Pipette 25ml sample(filtrate first if necessary) into a 500ml beaker

8.1.2. Slowly add about 40ml Sulfuric acid (98%), and then cover with

Watch glass

8.1.3. Heat up the mixed solution until it becomes clear(but still in deep

brown color) on Heater, which will take 20~40min.The gold will

form sponge.

8.1.4. Cool down, slowly & carefully add DI water to dilute left Sulfu ric

Acid;

8.1.5. Use boiled hot DI water to wash sponge 2 times, and carefully pour

out washing water to make sure no Au particle lost.

8.1.6. Add concentrated Nitric Acid 20ml to boil sponge 10min., and then

cool down.

8.1.7. Use boiled hot DI water to wash for a few times.

8.1.8 Transfer Au sponge & particles into weighted crucible(W1), and then

dry for 2hrs@150°C in a clean oven;

8.1.9. Switch off oven, and then cool down;

8.1.10 Put crucible into disccator for 20min., and then weight crucible

Again(W2)

Calculation:

Gold (g/L)=(W2-W1)x40

Note:

•Keep all washing solution & rinsing water in a big beaker, and mix well to verify Au concentration with AA machine after completion of

gravimetric analysis.

•To minimize possible big analysis error, normally total Au attracted by gravimetric method should be more than 0.2g. Thus, the sampling volume can be more or less than 25ml.

• A correlation in 900°C furnace >20min. show that there is no difference compared to 150°C oven dry 2hrs results.

8.2. Procedure for gold refining aqua regia solution

8.2.0 Prepare cleaned crucible same as 8.1.0

8.2.1 Pipette 25ml sample(filtrate first if necessary) into a 500ml beaker

8.2.2 Add 10ml concentrated HCl, and then add DI water to about 150ml,

mix well

8.2.3Slowly add total 5grams Sodium Sulfite anhydrous, and m ix well