Synthetic wollastonite

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01 February 2021 - 28 February 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: EUR 20268 EN 2002

Version / remarks:

Procedure designed to be compatible with the European Commission Technical Guidance Document EUR 20268 Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances (2002)

GLP compliance:

yes

Type of method:

other: Cascade Impaction and sieving

Type of particle tested:

primary particle

Type of distribution:

mass based distribution

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier): Imerys

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature, in the dark

No.:

#3

Size:

< 5.5 µm

Distribution:

0.167 %

No.:

#2

Size:

< 10 µm

Distribution:

0.649 %

No.:

#1

Size:

< 100 µm

Distribution:

96.9 %

Table 8 Results

Measurement	Result
Mass of test item transferred to sieve (W1)	11.04 g
Mass of test item passed through sieve (W3 – W2)	10.70 g
Percentage of test item less than 100 µm	96.9 %

Cascade Impactor
The results of the cascade impactor procedure are shown in the following table:

Table 9 Results

Collection Stage	Particle Size Range Collection	Collected Mass (g)
		Determination 1	Determination 2	Determination 3
Artificial throat	n/a	0.91	2.21	2.50
Sample Cup 1	> 10.0	2.0738	0.7555	0.4699
Sample Cup 2	5.5 to 10.0	0.0122	0.0160	0.0150
Sample Cup 3	2.4 to 5.5	0.0032	0.0039	0.0035
Sample Cup 4	1.61 to 2.4	0.0022	0.0001	0.0003
Sample Cup 5	0.307 to 1.61	0.0005	0.0002	0.0001
Final Filter	<0.3.07	0.0003	0.0006	0.0001
Total mass of collected test item		3.0022	2.9863	2.9889
Mass of test item added		2.9930	2.9955	2.9905

The cumulative amounts of test item collected in the three determinations for the individual particle size cut-points are shown in the following table:

Table 10 Overall Results

Particle Size Cut Points (µm)	Cumulative Mass (g)			Cumulative Percentage (%)
	Determination 1	Determination 2	Determination 3	Determination 1	Determination 2	Determination 3
<10.0	0.0184	0.0208	0.0190	0.613	0.697	0.636
<5.5	0.0062	0.0048	0.0040	0.207	0.161	0.134
<2.4	0.0030	0.0009	0.0005	0.100	0.030	0.017
<1.61	0.0008	0.0008	0.0002	0.027	0.027	0.007
<0.307	0.0003	0.0006	0.0001	0.010	0.020	0.003

Mean cumulative percentage with a particle size less than 10.0 μm: 0.649% Mean cumulative percentage with a particle size less than 5.5 μm: 0.167%

Conclusions:

Particle size data was acquired, using a procedure designed to be compatible with the European Commission Technical Guidance Document EUR 20268 Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances (2002). The results are as follows:

Percentage of test item with an inhalable particle size <100 μm - Sieve - 96.9%
Percentage of test item with a thoracic particle size <10.0 μm - Cascade Impactor - 0.649%
Percentage of test item with a respirable particle size <5.5 μm - Cascade Impactor - 0.167%

Reference 2

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

March 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

other: ISO 5753

Version / remarks:

Method for determining the content of respirable particles in a sample of a substance containing
crystalline silica.

GLP compliance:

not specified

Type of method:

other: Size Weighted Respirable Fraction

Type of particle tested:

agglomerate

Type of distribution:

volumetric distribution

No.:

#1

Distribution:

0.1 %

Remarks on result:

other: Mean result of 9 runs

Mineral Type	Malvern Laser Diff. (wt.%)Mie	Total Quartz (wt.%) XRD	Total Crystalline Silica (wt.%) XRD	Respirable Crystalline Silica wt.% (Calc.)	SWeRF (Sedimentation ) (wt.%)	Quartz in Respirable Fraction (wt.%) XRD	Cristobalite in Respirable Fraction (wt.%) XRD	Crystalline Silica in Respirable Fraction (wt.%) XRD	SWERF Respirable Crystalline Silica (wt.%) (Sedimentation)
Syn Wollastonite	35.33	1.14	1.14	0.4	1.9			2.5	0.05
Syn Wollastonite	45.27	1.32	1.32	0.6	2.2			2.1	0.05
Syn Wollastonite	6.72	1.7	1.7	0.11	2.25	1.7		1.7	0.04
Syn Wollastonite	6.37	1.35	1.35	0.09	2.75	1.35		1.35	0.04
Syn Wollastonite	7.67	1.43	1.43	0.11	2.82	1.43		1.43	0.04
Syn Wollastonite	47.78	0.59	0.59	0.28	41.35	0.5		0.5	0.21
Syn Wollastonite	33.39	0.85	0.85	0.28	29.77	0.7		0.7	0.21
Syn Wollastonite	33.42	0.78	0.78	0.26	27.69	0.69		0.69	0.19
Syn Wollastonite	58.06	0.28	0.28	0.16	33.02		0.32	0.32	0.11
Mean	30.4	1.04	1.04	0.26	15.97	1.06	0.32	1.25	0.10

Conclusions:

Analysis of the particle size distribution via the SWeRF method demonstrates that the substance typically contains <0.1 % respirable crystalline silica and the upper specification limit is <=0.21 %. On this basis, classification is not required.

Reference 3

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Principles of method if other than guideline:

Particle size distribution on medium grade soda-ash flux calcined kieselguhr was determined using a Coulter model LS 100 particle size analyzer

GLP compliance:

no

Type of distribution:

counted distribution

Percentile:

D50

Remarks on result:

other: Migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.

Percentile:

other: 81.6 %

Mean:

< 90 µm

Table 1: Results of particle size analysis

Diameter of particles µm	Volume % <	Diameter of particles µm	Volume % <
1	1.89	40	56.4
1.5	3.09	50	64.1
2	3.89	60	69.9
3	5.12	75	76.7
4	6.28	80	78.5
6	8.76	90	81.6
8	11.5	125	89.2
10	14.7	160	93.2
12	18.2	250	97
16	25.4	320	98.2
20	32.2	400	99.1
24	38.3	500	99.7
28	43.7	600	99.95

Conclusions:

The particle size distribution test indicates that the medium grade material has 81.6% < 90 µm. The substance is therefore considered to be inhalable.

Reference 4

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Principles of method if other than guideline:

Particle size distribution on fine and coarse grade soda-ash flux calcined kieselguhr was determined using a Coulter model LS 100 particle size analyzer

Type of distribution:

counted distribution

Percentile:

D50

Remarks on result:

other: Migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.

Percentile:

other: 59.5%

Mean:

< 90 µm

Remarks on result:

other: Coarse grade

Percentile:

other: 99.6%

Mean:

< 90 µm

Remarks on result:

other: Fine grade

Table 1: Results of particle size analysis on coarse grade

Diameter of particles	Volume % <	Diameter of particles	Volume % <
1	0.68	40	24.4
1.5	1.18	50	32.1
2	1.56	60	39.5
3	2.09	75	50
4	2.49	80	53.3
6	3.18	90	59.5
8	3.84	125	76.4
10	4.56	160	86.6
12	5.39	250	96.2
16	7.3	320	98.3
20	9.59	400	99.3
24	12.2	500	99.8
28	15.1	600	99.98
32	18.2

Table 2: Results of particle size analysis on fine grade

Diameter of particles	Volume % <	Diameter of particles	Volume % <
1	3.81	40	98.4
1.5	6.81	50	99.1
2	9.63	60	99.3
3	15.7	75	99.5
4	22.3	80	99.5
6	35.3	90	99.6
8	47.4	125	99.8
10	58.7	160	99.9
12	68.6	250	99.996
16	82.7	320	100
20	90.3	400	100
24	94	500	100
28	95.9	600	100
32	97.1

Conclusions:

The particle size distribution test shows that the coarse grade has 59.5% < 90µm and the fine grade has 99.6% < 90µm. Both grades of the substance are considered to be inhalable.

Reference 5

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well-reported study

Qualifier:

according to guideline

Guideline:

other: The particle size distribution of the calcium silicate is measured using a Leeds and Northrup X100 particle size analyser

Version / remarks:

The particle size distribution of the calcium silicate is measured using a Leeds and Northrup X100 particle size analyser (which uses a laser diffraction technique to compute a particle size distribution chart). The data from the particle size analysis are then entered into the SWeRFcs calculation spreadsheet in order to determine the respirable crystalline silica content of the product.

Deviations:

no

Principles of method if other than guideline:

The particle size distribution was determined using a Leeds and Northrup X100 particle size analyser

GLP compliance:

no

Type of method:

other: The particle size distribution of the calcium silicate is measured using a Leeds and Northrup X100 particle size analyser

Remarks:

laser diffraction technique to compute a particle size distribution chart). The data from the particle size analysis are then entered into the SWeRFcs calculation spreadsheet in order to determine the respirable crystalline silica content of the product.

Type of distribution:

volumetric distribution

Key result

Percentile:

D50

Remarks on result:

other: Migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.

Key result

Percentile:

D50

Mean:

20.805 µm

Remarks on result:

other: no data on SD

Key result

Percentile:

D90

Mean:

37.185 µm

Remarks on result:

other: no data on SD

Key result

Percentile:

D10

Mean:

11.177 µm

Remarks on result:

other: no data on SD

The respirable crystalline silica content determined by entering the output from the particle size distribution analysis into the SWeRFcs calculation spreadsheet was <0.1 %.

Conclusions:

The respirable crystalline silica content determined by entering the output from the particle size distribution analysis into the SWeRFcs calculation spreadsheet was <0.1 %.

Executive summary:

Particle size analysis of a typical batch of calcium silicate showed the D10, D50 and D90 to be 11.18, 20.81 and 37.19 microns, respectively. Analysis of the data using the SWeRFcs calculation spreadsheet showed the respirable crystalline silica (RCS) content to be < 0.1 %. The specification limit for RCS is 0.9 %.

Description of key information

Particle size distribution analysis of Synthetic wollastonite gave results of 96.9% <100 µm, 0.649% <10 µm and 0.167% < 5.5 µm.

Additional information

Particle size data was acquired, using a procedure designed to be compatible with the European Commission Technical Guidance Document EUR 20268 Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances (2002).