# US 10,502,700 B2 · Methods for analyzing respirable particles in bulk materials

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- Number: US 10,502,700 B2
- Document ID: US10502700B2
- Status: Granted
- Kind: B2
- Application number: 15/642,533
- Filed: 2017-07-06
- Published: 2018-01-18
- Granted: 2019-12-10
- Earliest claimed: 2016-07-12
- Assignees: United States Gypsum Company
- Applicants: United States Gypsum Company
- Inventors: James W. Barber; Feng Peng
- Web page: https://patentgrep.com/patent/US10502700B2

## CPC

- G01N 23/2206: Combination of two or more measurements, at least one measurement being that of secondary emission, e.g. combination of secondary electron [SE] measurement and back-scattered electron [BSE] measurement
- G01N 1/4005: {by transferring a selected component through a membrane}
- G01N 15/1456: {without spatial resolution of the texture or inner structure of the particle, e.g. processing of pulse signals}
- G01N 15/1468: {with spatial resolution of the texture or inner structure of the particle}
- G01N 23/20091: Measuring the energy-dispersion spectrum [EDS] of diffracted radiation
- G01N 23/2251: using incident electron beams, e.g. scanning electron microscopy [SEM]
- G01N 15/0625: {Optical scan of the deposits}
- G01N 23/2005: Preparation of powder samples therefor
- G01N 2015/0061: {in solids, e.g. petrography}
- G01N 2015/1497: {Particle shape}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Provided is a method for detecting respirable participles in a bulk material comprising particles. The method comprises: analyzing morphology of the particles; analyzing chemical composition of the particles; creating a profile of the particles, wherein each particle in the profile is characterized by its shape, size and chemical composition; selecting particles from the profile which match the size and chemical composition of a respirable particle; and calculating a percentage of the respirable particles in the bulk material.

## Claims

### Claim 1

A method for detecting respirable participles in a bulk material sample comprising particles, the method comprising:
weighing the bulk material sample;
resuspending the particles of the bulk material sample in a medium selected from water and/or organic solvent, and filtering the suspension through a filter with a nominal pore size sufficiently small to retain the particles in the respirable size range;
analyzing morphology of the particles;
analyzing chemical composition of the particles;
creating a profile of the particles, wherein each particle in the profile is characterized by its shape, size and chemical composition;
counting the particles as a total number of the particles in the bulk material sample;
selecting particles from the profile which match the size smaller than 20 microns and chemical composition of a respirable particle comprising silica (SiO2);
counting the selected particles as respirable particles; and
calculating a percentage of the respirable particles from the total number of the particles in the bulk material sample.

### Claim 2 (depends on 1)

The method of claim 1, wherein the morphology and chemical composition of the particles are analyzed by a scanning electron microscope interfaced with an energy dispersive X-ray spectrometer.

### Claim 3 (depends on 1)

The method of claim 1, wherein the particles are retained on a filter, and wherein the morphology and chemical composition of the particles are analyzed by a scanning electron microscope interfaced with an energy dispersive X-ray spectrometer.

### Claim 4 (depends on 1)

The method of claim 1, wherein the bulk material is a mixture of inorganic compounds.

### Claim 5 (depends on 1)

The method of claim 1, wherein the respirable particles are smaller than 10 microns.

### Claim 6 (depends on 1)

The method of claim 1, wherein the bulk material is selected from the group consisting of gypsum and calcium carbonate.

### Claim 7 (depends on 1)

The method of claim 1, wherein the filter is a polycarbonate filter.