James D. Grenia

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Concord, CA, US

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Patents Grantslast 30 patents

Information Patent Grant
Method of mining of thick seam materials
- Patent number 4,213,653
- Issue date Jul 22, 1980
- Bechtel International Corporation
- James D. Grenia
- E21 - EARTH DRILLING MINING
Information Patent Grant
Underground formed wall single-entry mining method
- Patent number 4,174,135
- Issue date Nov 13, 1979
- Bechtel International Corporation
- James D. Grenia
- E21 - EARTH DRILLING MINING