# US 4,400,034 A · Coal comminution and recovery process using gas drying

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- Number: US 4,400,034 A
- Document ID: US4400034A
- Status: Granted
- Kind: A
- Application number: 06/232,618
- Filed: 1981-02-09
- Granted: 1983-08-23
- Earliest claimed: 1981-02-09
- Assignees: Mobil Oil Corporation
- Inventors: Ju-Nam Chew
- Web page: https://patentgrep.com/patent/US4400034A

## CPC

- E21B 43/243: Combustion in situ
- E21B 43/2605: {using gas or liquefied gas}
- E21B 43/28: Dissolving minerals other than hydrocarbons, e.g. by an alkaline or acid leaching agent (E21B43/241 takes precedence)
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

This invention is a comminution process for treating coal with a drying gas to form fractures which weaken the structure of the coal and make it easier to disintegrate mechanically, chemically or by fluid force. Another aspect of this invention is a process for treating an underground formation of coal with a dry gas for a time sufficient to form cracks and fractures in a portion of the formation in order to increase the permeability of the coal formation to the flow of fluids therethrough. Processes for in-situ combustion of the coal formation are therefore more efficient since the coal formation is more permeable to the flow of gas therethrough.

## Claims

### Claim 1

An improved process for comminuting coal wherein the coal is treated with an effective amount of a solvent selected from the group consisting of a basic aqueous solution and methanol, the improvement comprising first contacting said coal with a drying gas and continuing to contact said coal with said drying gas for a time sufficient to fracture at least a portion of said coal by the absorption of moisture from the coal thereby enhancing comminution.

### Claim 2 (depends on 1)

The process of claim 1 wherein said basic aqueous solution is selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and ammonia.

### Claim 3 (depends on 1)

The process of claim 1 wherein said drying gas is selected from the group consisting of air, argon, helium, carbon dioxide, methane, oxygen, oxygen-enriched air and nitrogen.

### Claim 4 (depends on 1)

The process of claim 1 wherein the temperature of said dry gas is between 20.degree. C. and 150.degree. C.

### Claim 5

An improved process for comminuting coal wherein the coal is treated with an effective amount of gaseous anhydrous ammonia, the improvement comprising first contacting said coal with a drying gas and continuing to contact said coal with said drying gas for a time sufficient to fracture at least a portion of said coal by the absorption of moisture from the coal thereby enhancing comminution.

### Claim 6 (depends on 5)

The process of claim 5 wherein said drying gas is selected from the group consisting of air, argon, helium, carbon dioxide, methane, oxygen, oxygen-enriched air and nitrogen.

### Claim 7 (depends on 5)

The process of claim 5 wherein the temperature of said drying gas is between 20.degree. C. and 150.degree. C.

### Claim 8

In a process for recovering subterranean coal which comprises contacting a coal seam in-situ with a basic aqueous solution and maintaining said contact for a time sufficient to fragment at least a portion of said coal, disintegrating said portion to form a slurry, and transporting said slurry to the earth's surface to a storage vessel, the improvement comprising first injecting into the coal seam a drying gas; continuing to inject said dry gas into said coal seam for a time sufficient to fracture at least a portion of said coal by the absorption of moisture from the coal; and withdrawing moistened gas from the coal seam.

### Claim 9 (depends on 8)

The process of claim 8 wherein said drying gas is selected from the group consisting of air, argon, helium, carbon dioxide, methane, oxygen, oxygen-enriched air and nitrogen.

### Claim 10 (depends on 8)

The process of claim 8 wherein the temperature of said drying is between 20.degree. C. and 150.degree. C.

### Claim 11 (depends on 8)

The process of claim 8 wherein said basic aqueous solution is selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.