System and method for on-line monitoring and control of heavy metal contamination in soil washing process

• US 5,414,195 A
• Filed: 06/17/1992
• Issued: 05/09/1995
• Est. Priority Date: 03/01/1991
• Status: Expired due to Fees

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Congedo, Thomas V., Peterson, Steven H., Partlow, William D., Sverdrup, Edward F., Witkowski, Robert E., Skriba, Michael C., Lahoda, Edward J., Grant, David C., Wolfe, Arthur L., Bartko, John
• Primary Examiner(s): Walsh, Donald P.
• Assistant Examiner(s): JENKINS, DANIEL J
• Application Number:
  US07/899,962
• Time in Patent Office: 1,056 Days
• Field of Search: 422/186, 422/50, 422/62, 422/68.1, 588/231, 588/900, 588/1, 378/53, 378/88, 209/576, 209/577, 209/578, 209/579, 209/589, 209/2
• US Class Current: 588/1
• CPC Class Codes: G01N 21/718 Laser microanalysis, i.e. with formation of sample plasma
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids
• CPC Class Codes: G01N 23/12 the material being a flowing fluid or a flowing granular solid
• CPC Class Codes: Y10S 588/90 Apparatus

Abstract

The concentrations of residual heavy metal contaminants in the particulate material in a slurry produced in a particulate material washing process are monitored on-line and can be used to control the washing process. In alternative embodiments of the invention, x-rays, thermal neutrons or laser beams are directed at the slurry as it flows through a flow cell to induce emission of secondary x-rays, gamma rays or light, respectively, characteristic of the heavy metal contaminants and constituents representative of the solids contents of the slurry. These characteristic energies are measured and used to determine the concentration in ppm of the residual heavy metal contaminants in the particulate material within the slurry.

Claims

1. A system for washing particulate material, including soil, contaminated by one or more contaminants, said system including means processing said particulate material to produce a flow of a stream including particulate material having residual contaminants in a concentration of less than about 1000 ppm of particulate material, the improvement comprising:

means for on-line monitoring of the concentration of said residual contaminants in the particulate material in said stream including;

means applying energy to said slurry to produce characteristic electromagnetic radiation from constituents in said stream including said residual contaminants, and analyzing means analyzing the electromagnetic radiation produced to measure an amount of characteristic electromagnetic radiation emitted by the residual contaminants and an amount of electromagnetic radiation representative of at least one other constituent of the particulate material in the stream to which said energy is applied that is substantially homogeneously present therein, and determining from said amount of residual contaminants and from the amount of radiation representative of the particulate material in the slurry the concentration of said residual contaminants in said particulate material; and

means responsive to the concentration of contaminants in the particulate material in the stream to adjust the means processing the particulate material to change the level of residual contaminants in the stream.

2. The system of claim 1 wherein said means applying said energy to said slurry comprises apparatus applying x-rays to a flowing sample of said slurry to produce characteristic x-ray radiation from constituents in said slurry contaminants, and wherein said means analyzing said characteristic electromagnetic radiation includes x-ray detectors.

3. The system of claim 1 wherein said analyzing means includes a neural network conditioned with slurry samples containing varying concentrations of residual contaminants and particulate material for determining on-line the concentration of residual contaminants in said particulate material in said slurry.

4. The system of claim 1 wherein said means applying energy to said slurry comprises means bombarding said particulate material with neutrons inducing constituents in said particulate material including said residual contaminants to emit characteristic gamma rays and means analyzing said gamma rays to determine the magnitude of the gamma rays emitted by said residual contaminants and the magnitude of gamma rays emitted by one more selected other constituents related to the amount of particulate material present in said slurry, and determining from the magnitudes of said gamma rays, the concentration of said contaminants in said particulate material.

5. The system of claim 1 wherein said means for applying energy to said slurry comprises means directing a laser beam at a portion of said slurry to vaporize and breakdown constituents in said slurry into characteristic light, and wherein said analyzing means comprises means determining the magnitude of characteristic light emitted by said contaminants, and characteristic light emitted by one or more constituents present substantially homogeneously in said particulate material and determining therefrom the concentration of contaminants in the particulate material in said slurry.