Technical manual section 12

Standard Test Method for Determination of the Acid Absorption of Leady Oxide Produced by the Barton or Ball Mill Methods………... STANDARD TEST METHOD FOR DETERMINATION OF THE AMOUNT OF FR

BCI Battery Technical Manual

BCIS-12

REV JUNE

2008

Approval Submission: April, 2008 Revised: August, 2008

BCI RECOMMENDED TEST PROCEDURES FOR LEAD OXIDE

TABLE OF CONTENTS

1 Standard Test Method for Determination of the Amount of Free Lead in Leady Oxide

Produced by the Barton or Ball Mill Method (Method A-Acetic Acid Dissolution Procedure) 2

1.1 Scope 2

1.2 Significance and Use 2

1.3 Safety 2

1.4 Apparatus and Materials 2

1.5 Procedure 3

1.6 Calculation 3

2 Standard Test Method for Determination of Apparent Density of Leady Oxides Produced by the Ball Mill or Barton Processes 4

2.1 Scope 4

2.2 Significance and Use 4

2.3 Method 4

2.4 Equipment 4

2.5 Procedure 5

3 Standard Test Method for Determination of the Acid Absorption of Leady Oxide Produced

by the Barton or Ball Mill Methods……… 7

3.1 Scope 7

3.2 Significance and Use 7

3.3 Safety 7

3.4 Procedure 8

3.5 Calculation 9

4 Standard Test Method for Determination of Lead Sulfate, Lead Monixided and Lead 11

Dioxide in Formed Positive Plates of Lead Acid Batteries 4.1 Scope 11

4.2 Significance and Use 11

4.3 Safety 11

4.4 Apparatus and Reagents 11

4.5 Procedure 12

4.6 Calculations 12

1 STANDARD TEST METHOD FOR DETERMINATION OF THE AMOUNT OF FREE LEAD IN LEADY OXIDE PRODUCED BY THE BARTON OR BALL MILL METHOD

METHOD A – ACETIC ACID DISSOLUTION PROCEDURE

1.1.1 This procedure provides a test method to determine the amount of free lead in leady oxide

produced by either the Barton or the ball milling processes It is used to determine the amount of free lead metal in the leady oxide used for production of pastes for positive and negative plates

1.2 SIGNIFICANCE AND USE:

1.2.1 Accurate control and measurement of the amount of free lead in leady oxide is important in

the battery industry The amount of free lead in the paste mix affects the properties of the paste, the plate, the curing process and the performance of the battery

1.2.2 Battery manufacturers specify the amount of free lead in leady oxide to control the quality of

the oxide used in batteries It is vital that an accurate and repeatable method is available to determine this property

1.2.3 An operating range of free lead values of 18% - 30% may be experienced depending on the

type of oxide

1.2.4 Reagent quantity limits are determined by sample size and free lead concentration and may

be adjusted by the user to achieve the desired operating range

1.2.5 Precision, expressed as standard deviation, may be determined by repeated analysis (10-20

replicates) of a reference oxide standard

1.3.1 Leady oxide is a poisonous material and proper occupational safety procedures should be

followed whenever it is handled

1.3.2 This procedure should be carried out in a fume hood, and eye protection equipment and acid

resistant gloves should be worn Suitable approved receptacles should be available for the disposal of lead waste

1.4.1 25% acetic acid solution by volume (1 part of glacial acetic acid to 3 parts of tap

water)

1.4.2 Clean tap water

1.4.3 250ml glass beaker

1.4.4 Cover glass

1.4.5 Glass stirring rod

1.4.6 Balance, accuracy ±0.1 grams

1.4.7 Electric hot plate

1.4.8 Acetone

1.5 PROCEDURE

1.5.1 Tare a clean and dry 250ml beaker on the balance

1.5.1.1 Add 20±0.1g of leady oxide to the beaker Record weight as Lo.

Note: A larger sample may be used when analyzing oxide samples that have free lead contents lower than 10% In this case the amount of water and 25% acetic acid must be increased accordingly

1.5.1.2 If a different sample size is used it should be weighed to a precision of ± 0.1g

1.5.2 Add 25±1ml of water and mix thoroughly with the glass stirring rod Leave the rod in the

beaker

1.5.3 Add 125±1ml of 25% acetic acid solution Stir the contents briefly to ensure that any floating

oxide is wetted

1.5.4 Place the 250ml beaker on a hot plate in an approved fume hood Place a cover glass on the

beaker to prevent spattering

1.5.5 Turn the hot plate on Gently boil the contents until the solution clears The free lead residue

will congeal into a loose mass

1.5.6 Stir the solution with a glass stirring rod Form the free lead residue into a ball or pancake

taking care that all pieces are agglomerated

1.5.7 Decant the clear solution into a lead waste disposal vessel making sure that the free lead

residue is not transferred

1.5.8 Wash the lead ball or pancake thoroughly with water in the beaker

1.5.9 Remove from the beaker and wash with water

1.5.10 Squeeze the ball or pancake tightly to remove as much water as possible (this can be done

by pressing the ball or pancake onto a filter paper with the blade of a spatula), or wash with acetone

1.5.11 Place the lead ball or pancake on a watch glass and transfer to a hot plate or oven at 150ºC

(300ºF)

1.5.12 Dry quickly to reduce oxidation

1.5.13 Remove the lead ball from the watch glass Weigh the dried lead ball or pancake to the

nearest 0.1g Record the weight as Lf

Note: A reduction in weight as the ball is drying is an indication that it is not completely dry In this case the ball should be dried further until a constant weight is obtained from two

successive weights taken 5 minutes apart

1.5.14 Dispose of the lead ball in a suitable approved hazardous waste container

1.6.1 Calculate the free lead by dividing the amount of undissolved lead from Step 5.14 obtained

by the above procedure by the starting amount of leady oxide

% free lead = [Lf / Lo] x 100

2 STANDARD TEST METHOD FOR DETERMINATION OF APPARENT DENSITY OF

LEADY OXIDES PRODUCED BY THE BALL MILL OR BARTON PROCESSES

2.1.1 This procedure covers determination of the apparent density of the leady oxides used in

lead-acid battery paste and plate making by passing leady oxide through a bolting cloth screen and vibrating over a set of baffles into a calibrated one cubic inch or 10 cubic centimeter apparent density cup (also referred to as a cube cup) The tared cup is then weighed The apparent density is determined from the weight of material in the cup

2.1.2 The customary units used by the battery industry for this property are grams per cubic inch

(g/in3) or grams per cubic centimeter (g/cm3).

2.1.3 This method is suitable for all grades of leady oxide used by the lead-acid battery industry

2.2.1 The apparent density of leady oxide is a measure of its coarseness and its control is vital for

the performance and life of lead-acid batteries Apparent density is used to verify that the leady oxide is suitable for the type of battery being produced A value is usually specified by the battery manufacturer to ensure that the oxide is suitable for the intended function It is important that the method be reliable, accurate and repeatable

2.2.2 This method is suitable for leady oxides produced by the Barton and ball milling processes

2.2.3 An operating range of values of 10-40 g/cm3 may be experienced depending on the type of

oxide

2.2.4 Precision, expressed as standard deviation, may be determined by repeated analysis (10-20

replicates) of a reference oxide standard

2.3.1 The material is passed through a bolting cloth screen and vibrated over a set of baffles into a

calibrated one cubic inch or 10 cubic centimeter apparent density cup The cup is weighed The apparent density can be determined from the weight of the material in the cup and is expressed in g/in3 or g/cm3.

2.4.1 Scott volumeter(1) fitted with bell buzzer (see Figure 1)

2.4.2 74 mesh bolting cloth or equivalent as determined by the user

2.4.3 Soft bristle brush, 7/8 inches diameter x 1-1/8 inches in length or equivalent

2.4.4 Apparent density cup(2), volume equal to1.0±0.003 in3 or 10.0±0.001 cm3

2.4.5 Balance (accuracy ± 0.1 gm.)

2.4.6 Flat bladed spatula

2.5 PROCEDURE

2.5.1 Determine and record the tare weight of the clean apparent density cup that will be used in

this procedure

2.5.2 Clean the volumeter, then place the weighed cup directly under the baffle plates of the clean

volumeter Pour the oxide that is being tested into the funnel of the volumeter and, with the buzzer running at the lowest setting, brush the oxide through the 74 mesh bolting cloth screen until the cup is slightly overfilled Take care not to move or vibrate the cup since this will cause the oxide to be compacted and increase the apparent density

2.5.3 Using the spatula with the blade angled backwards at approximately 45º, scrape excess

oxide off the top and rim of the cup This should be done in a smooth motion to avoid

disturbing the oxide in the cup After scraping, tap the cup to settle the oxide to prevent spilling

2.5.4 Weigh the filled cup to the nearest ±0.1g and calculate the weight of oxide by subtracting the

tare weight

2.5.5 If using a cup in English units, the apparent density expressed as g/in3 is the weight of oxide

in the 1 cubic inch cup If using a metric cup, the apparent density expressed as g/cm3is the weight of oxide divided by the cup volume This number is 10 for a 10cm3cup

Note:

(1), (2) Available from: Eagle Oxide Services, Inc., 5677 West 73rd Street, Indianapolis, Indiana 46278-1739, USA

Telephone: (317) 290-8485

Facsimile: (317) 290-8766

e-mail: eaglesales@eagleoxide.com

www.eagleoxide.com

Figure 1

Scott Volumeter for Determination of Apparent Density

3 STANDARD TEST METHOD FOR DETERMINATION OF THE ACID ABSORPTION OF

LEADY OXIDE PRODUCED BY THE BARTON OR BALL MILL METHODS

3.1.1 This procedure applies to leady oxides produced by the Barton and ball milling

processes It is used to determine the reactivity of these oxides with sulphuric acid during production of pastes used for positive and negative plates This reactivity is expressed as

an acid absorption number (mg of H2SO4 per gof oxide)

3.2.1 Accurate control of the reactivity of leady oxide with sulphuric acid is important in the

battery industry It affects the properties of the paste and the performance of the plates that are produced from the paste For example, an oxide having a higher reactivity will give a higher paste temperature during paste mixing and will yield a plate having increased performance at high rates of discharge Oxide reactivity (acid absorption) depends on the particle size distribution of the oxide Oxides with larger particles will have a lower reactivity with sulphuric acid than oxides with smaller particles The acid absorption of lead oxides is an indirect determination of their relative particle sizes and surface areas based on the rate of reaction between the oxides and sulfuric acid under

specified conditions of concentration, temperature, time and agitation

3.2.2 Battery oxide manufacturers control the acid absorption of leady oxide to control the

quality of the oxide used in batteries Battery manufacturers specify acid absorption to assure that the correct oxide is used for the type of battery being manufactured It is vital that an accurate and repeatable method is available to measure this property

3.2.3 An operating range of acid absorption values from 140mg.g-1 – 240mg.g-1 may be

experienced depending on the type of oxide

3.2.4 Precision, expressed as standard deviation, may be determined by repeated analysis

(10-20 replicates) of a reference oxide standard

3.3.1 Leady oxide is a poisonous material and proper occupational safety procedures should

be followed whenever it is handled

3.3.2 This procedure involves the use of sulphuric acid Protective clothing, eye protection

equipment and acid resistant gloves should be worn Suitable approved receptacles should be available for disposal of lead and acid waste

3.3.3.1 Apparatus

3.3.3.1.1 Mechanical shaker unit or equivalent (1) as shown in Figure 1

3.3.3.1.2 0°C - 100°C NIST Certified thermometer

3.3.3.1.3 60 minute timer with accuracy of ±1 second

3.3.3.1.4 25 ml Pipette (Precision Grade)

3.3.3.1.5 Burettes

3.3.3.1.5.1 50 ml (Precision Grade)

3.3.3.1.5.2 100 ml (Precision Grade)

3.3.3.1.6 500 ml Bottle (16 oz., wide mouth, height 152.4mm (6in )overall, outside

diameter 82.55mm (3.25in), inside mouth diameter 25.4mm (1.0in) fitted with #9

or #10 rubber stopper), or similar stoppered container

3.3.3.1.7 Two 20 liter (~5 gal) Nalgene bottles or equivalent, with rubber stoppers, for

standard solutions of KOH & H2SO4 3.3.3.1.8 50ml Erlenmeyer flask

3.3.3.1.9 250ml filtering flask

3.3.3.1.10 Buchner funnel, 9cm (3.5in) outside diameter

3.3.3.1.11 #1 Whatman filter paper, 9cm diameter

3.3.3.1.12 Pipette bulb

3.3.3.1.13 Heavy duty plastic bag

3.3.3.2 Reagents

3.3.3.2.1 Standard Potassium Hydroxide

3.3.3.2.1.1 Dissolve 1250g of potassium hydroxide (reagent grade) in distilled water and

dilute to 19 liters in a storage bottle Let stand overnight to cool to 25.0±0.5ºC (77.0±1.0ºF) before standardization To standardize, dissolve approximately 5g (weighed accurately) of NBS standard potassium acid phthalate (KHC8H4O4) in 200ml of distilled water Titrate with standard potassium hydroxide using 1% phenolphthalein indicator (dissolve 1 gm of phenolphthalein in 100 ml of 50% ethanol in water)

Normality of KOH = [(wt KHC 8 H 4 O 4 / 204.22) / ml KOH] × 1000

3.3.3.2.2 Standard Sulfuric Acid

3.3.3.2.2.1 Specific gravity, 1.100±0.001 at 25ºC containing not less than 0.1600 or more

than 0.1700 g of H2SO4 per ml To make up 19 liters of this acid, add 1800 ml of concentrated sulfuric acid (s.g.1.830) slowly, and with constant stirring, to 15

liters of distilled water (Caution: Add the acid slowly and do not add water

to the acid) Adjust the final volume to 19.4 liters Cool overnight to 25±0.5ºC

(77.0±1.0ºF) and standardize 25.0ml of the acid against the previously standardized potassium hydroxide solution using 3-5 drops of the phenolphthalein solution as indicator Calculate the concentration in terms of

H2SO4 per ml The final acid concentration should be in the range of 3.26 to 3.47N H+

Normality H + = ( Normality KOH × ml KOH ) / 25.0 ml

3.4.1 Adjust the temperature of the acid absorption box to 32.2 ±0.5ºC (90.0±1.0ºF) 3.4.2 Transfer exactly 100 ml of sulfuric acid into the dry 500 ml bottle Stopper the

bottle and place in a hot water bath until the temperature has stabilized at 32.2±0.5ºC When the temperature has stabilized at 32.2+0.5ºC place the warm bottle inside the acid absorption box It is also permissible to place the bottle

inside the acid absorption box until the temperature has stabilized at 32.2+0.5ºC

(2)

3.4.3.1 Note: The acid absorption of leady oxide will be changed by exposure to air This

Is caused primarily by oxidation of free lead Samples shall be taken in a manner

to insure minimum exposure to air They shall be placed in a clean container and tightly sealed without delay and with minimum of handling The sample container shall be filled completely so as to leave minimum air space above the sample 3.4.3.2 Note: Remove approximately 3mm (0.125in.) of oxide from the top of the sample

before screening

3.4.4 Remove the bottle from the acid absorption box and add the oxide to the acid

slowly and uniformly over a period of 25-30s Start the timer as soon as the oxide contacts the acid in the bottle

3.4.5 Stopper the bottle immediately and invert, end-over-end, three times and place in

the acid absorption box shaker Start the shaker The total elapsed time from the beginning of the screening operation to the introduction into the shaker unit must not exceed 3 minutes

3.4.6 Rotate the bottle in the shaker at a rate of 17-19rpm until 10 minutes have e

lapsed on the timer from the beginning of the addition of the oxide to the acid 3.4.7 At the end of the 10-minute period, remove the bottle from the shaker unit and

allow the oxide to settle for 5 minutes at 25±0.5ºC (77.0±1.0ºF)

3.4.8 Filter the reacted acid under vacuum through the dry #1 Whatman filter paper on

the Buchner funnel into the filtering flask (initially wet the filter paper with the clear portion of reacted acid to ensure a good vacuum)

3.4.9 Cool the filtrate to 25±0.5ºC (77 ± 1.0°F) and pipette 25ml into a 250ml

Erlenmeyer flask Titrate with standard potassium hydroxide solution using 3-5 drops of phenolphthalein as indicator

3.4.10 Pipette 25 ml of the standard acid (at 25±0.5ºC (77.0±1.0ºF)) and titrate similarly

as a blank

3.5.1 The acid absorption number represents the milligrams of H2SO4 per gram of

oxide which have reacted with the sulfuric acid as determined by the difference in acid concentration before and after the reaction with the oxide

3.5.2 Acid Absorption Number = ( A - B ) × N × 3.923

Where: A = ml KOH for the blank titration

B = ml KOH for sample titration

N = Normality of standard KOH solution 3.923 = (Gram equivalent weight of H2SO4)/ (Wt of sample reacted with 25ml H2SO4) = 49/12.5

3.5.3.2 Blank Titration= 85.32ml

3.5.3.3 Sample titration= 38.60ml

3.5.3.4 Acid absorption = (85.32-38.60) x 0.9741 x 3.923

= 179mg H2SO4/g leady oxide

Figure 1 Acid Absorption Apparatus

(1) Available from: Eagle Oxide Services, P.O Box 78093, 5677 West 73rd Street, Indianapolis, Indiana 46278, USA

eaglesales@eagleoxide.com

(2) Available from: Sefar Filtration, Inc., 5 Locust Lane, Pittsburgh, Pennsylvania 15241, USA Brad.schreiber@sefar.us www.sefar.us

Electric Oven

Thermometer Gearmotor

Bottle Tumbler