Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Chemical analysis
Reexamination Certificate
1998-04-15
2001-01-23
Hoff, Marc S. (Department: 2764)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Chemical analysis
C702S022000, C073S863410, C073S864210, C356S417000
Reexamination Certificate
active
06178383
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to on-line sampling and analysis of a solid particulate suspended in a fluid, such as a phosphate rock, other minerals, grains, seed and other solids suspended in water, air, or other liquids or gases. More particularly, the invention relates to positioning a vortex tube in a process stream above a sample presentation area such as a light transparent window for removing deposited particulates, such as phosphates, and allowing for the collection of subsequent samples, in which the vortex tube provides a bypass to return the particulate samples to the flow downstream of the sample presentation area for continuous operation without interruption of the flow in the sampling line.
2. Description of the Related Art
Presently, phosphate rock is recovered from a sand-clay mixture that is mined from mineral deposits. Industrial recovery of solids of a few millimeters or less, such as phosphate rock, e.g., <1 mm, begins with chemical treatment of a liquid aqueous slurry which includes a long chain hydrocarbon liquid. These hydrocarbons attach to the phosphate rock and are hydrophobic in nature. Thus, after they attach to the rock, the phosphate rock is forced out of the water phase to the surface in an aeration tank called a flotation cell. The flotation cell must be monitored to ensure maximum recovery of the phosphate rock. The phosphate content in the slurry exiting the flotation cell after the removal of the hydrocarbon-bound phosphate rock, also known as tailings, is a representative indicator of flotation cell performance.
Phosphate rock found in the tailings is considered unrecoverable and a lost natural resource. Normal operation of the flotation cell involves operator estimation of cell performance by visual inspection of the tailings. To optimize the operator's control of the flotation cell, it would be desirable therefore to provide a system and a method of continuously monitoring phosphate tailings to provide feedback to the operator to improve the performance and efficiency of the flotation cell operation. To this end, it is usually desirable to maintain the %BPL content in the tailings streams below 3% for acceptable cell performance.
U.S. Pat. No. 5,396,260 to Adel et al. for “Video Instrumentation for the Analysis of Mineral Content in Ores and Coal” issued Mar. 7, 1995, discloses the determination of mineral content using a video system in which digitized images having assigned gray levels are analyzed to determine the content of particular minerals in a coal slurry determined from the distribution of the gray levels. Slip streams are extracted from the tailings and feed lines which are allowed to pass through a thin sample chamber with flat glass plates on either side, the sample chamber being enclosed in a light type box with a video camera to provide a reflected light image for sample analysis. However, such slip streams extracted from the tailings and feed lines, are not in line with the tailings stream but merely tapped away from the fluid media being processed and may not be representative of the sampling of an on-line flowing slurry.
U.S. Pat. No. 4,797,550 to Nelson et al. for “Fiber Optic Detector for Flotation Cell Processing” issued Jan. 10, 1989 discloses a fiber optic detector submerged in a coal slurry to monitor a coal separation process. Light transmitted by an optical fiber is directed toward the slurry, and thus scattered by the slurry, from which a portion of the light is deflected back to the fiber optic detector, from which the light intensity reflected by the slurry is used to detect the mineral content in the slurry. Accordingly, only a small sample separated from the slurry is analyzed, which may not be representative of the on-line stream.
It would be desirable therefore to provide on-line sampling in which sampling of the particulate content in a fluid media is provided in-line with the process stream to collect representative particulate samples, such as phosphate rock and sand in a tailings line. An in-line sample presentation assembly would be advantageous for the collection of samples from the tailings where the sample could be returned to a slurry stream for continuous operation without interruption of the flow in the sampling line.
SUMMARY OF THE INVENTION
Typical particulate analysis techniques provide off-line analysis or tapping of relatively small representative samples of the particulates suspended in a fluid media. These are often difficult to correlate to current process conditions from the resultant data. An on-line analyzer provides faster and better feedback for adjusting process control parameters. The apparatus and method embodying the present invention provides on-line sampling and analysis of the content of a particulate composition having a particle size from about 0.1 to about 20 mm, which is suspended or slurried in a fluid, which may be a liquid or a gas, to provide a rapid analysis of the particulate composition. The use of the fluid stream discussed herein is generic to gas and liquid carrier media. In an important aspect, the invention provides a method and apparatus for the analysis of the phosphate rock content values in a flowing slurry stream. The phosphate analyzer is provided in-line with the tailings stream of a phosphate floatation process.
In one aspect, the method of invention employs visual light and a visual light characterizing detection device which uses a visual image of the particulates, such as grains or seed in suspension or a phosphate tailings slurry, to analyze the particulate sample. The on-line sampling apparatus collects and presents samples that are rapidly purged and resampled using a procedure in which particulate solids in a fluid stream in gas or liquid are accumulated, concentrated or packed in a vessel or container for in-line analysis. In another aspect the characterizing detection device used to analyze the samples may use X-ray, gamma-ray, neutron, alpha particle, or other radiation sources other than visual light where a sample is presented on an area not transparent to visual light, but which is transparent to the energy source. In a further aspect the characterizing detection device may employ magnetic, acoustic, ultra-sound, or other energy sources where the particulate sample is presented in a sample presentation area which is analyzed with the particulate sample packed for the application of the associated energy or force. Analysis using electromagnetic energy such as X-ray, ultra-violet, infra-red or other radiation sources other than visual light requires a sample presentation area with a window transparent to the energy being used. Another important aspect provides optical image analysis using a video camera normal to the sample deposited on the sample presentation area using a computer providing image processing of the samples. To capture this image, an inline mechanical delivery vortex assembly presents a representative sample to a video camera. The invention provides a uniform, stationary, and quickly removable particulate sample which is trapped and imaged by positioning a vortex tube in the process stream above the particulate sample presentation area for thereafter removing deposited particulates. The invention allows for the collection of subsequent particulate samples, in which the vortex tube provides a bypass to return samples to the flow downstream of the sample presentation area. In the invention, the particulate sample being analyzed is taken from the continually flowing stream of particulates suspended in the fluid media to provide a representative particulate sample without interruption of the flow.
According to the invention, the in-line analysis system introduces a sample of suspended or slurried particulate composition, such as a sand, phosphate, and water slurry stream into a vortex assembly. The slurry stream gravitationally deposits a particulate layer, such as sand and particulate phosphate on the bottom of the vortex assembly, which can be viewed throu
Coulter Thomas L.
Davidson Christopher L.
Klein Scott P.
Patterson Stanley A.
Pegram Stephen C.
Bui Bryan
Cargill Incorporated
Fitch Even Tabin & Flannery
Hoff Marc S.
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