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HOW DOES THE PHOSPHOLYZERtm MEASURE PHOSPHORUS ?
By flowing slurry or solution containing phosphorus through a tube surrounded by
magnets, phosphorus atoms are oriented (polarized). Polarized atoms of phosphorus will absorb radio energy of a certain frequency. A radio transmitter with frequency tuned for polarized phosphorus is arranged to
beam into the flowing stream. Each polarized atom of phosphorus, after absorbing radio frequency (RF) energy, retransmits RF energy but at a different specific frequency -- in essence becoming a tiny radio station.
The phosphorous measurement technology for this process is magnetic resonance.
The PHOSPHOLYZERtm is provided with detectors set to phosphorus frequency, and the amount (intensity) of phosphorus retransmitted RF energy indicates how much phosphorus is present. Measured intensity is then converted by calibration to BPL or P205 content
of the slurry. Simultaneously, hydrogen is measured by the same procedure to determine how much water is contained in the flowing slurry. These data enable calculation of slurry percent solids, and by further
calculation BPL of solids in the slurry is determined.
DOES THE SIZE OF PHOSPHORUS MATRIX PARTICLES OR VARIATION IN CHEMICAL FORM OF PHOSPHORUS CAUSE MEASUREMENT PROBLEMS?
The answer for practical purposes is no.
When radio energy is transmitted into a flowing slurry there is no influence of solids or other materials in penetration of RF energy beamed through solids and water at the
frequencies used. Likewise, retransmission of RF energy from phosphorus atoms is neither absorbed or changed by solids or liquids in the slurry to a measurable extent. The result is magnetic resonance has unique
ability to specifically measure phosphorus, hydrogen, and other amenable elements. The technique is simple and without sources of significant interference.
Chemical or crystalline forms of phosphorus minerals do not
influence the process of magnetic resonance to activate each phosphorus atom in the flow stream, and retransmission of absorbed RF energy at phosphorus resonant frequency for measurement. Time required to polarize
phosphorus atoms can be different according to crystalline state and phase of matter containing phosphorus. Because the polarization stage takes place in a flow stream prior to entering the magnetic resonance sensor where
activation and measurement take place, differences in polarization times do not introduce error when sufficient polarization time for all forms of phosphorus is provided.
DOES THE METHOD EMPLOY RADIOISOTOPES OR OTHER
BIOLOGICALLY INTERACTIVE RADIATION?
Safety hazards associated with X-ray analysis, gamma-ray neutron analysis, and other high enegy radiation measurement techniques do not exist with magnetic resonance. No
radioactive isotopes or other sources of biologidally damaging radiation are involved with magnetic resonance on-stream analysis.
HOW MUCH EXPERIENCE HAS THERE BEEN WlTH MAGNETIC RESONANCE ON-STREAM ANALYSIS TO
ASSURE RELIABLILTY OF OPERATION?
Two PHOS PHOLYZERtm on-stream analyzer systems have been installed as production units in phosphate benefication plants. The first unit operated intermittently on a semi-production basis for two years until mine shutdown May 1992. The second analyzer was installed in 1992 and has been on operational status since late 1993. The user encountered sample handling problems along the way not associated with the PHOSPHOLYZERtm, but nontheless causing system downtime. These problems were overcome during the next year of operation and the second PHOSPHOLYZERtm system is now considered a "user friendly" production unit and is treated as such in routine operation. It has been incorporated into the plant distributed control system at the beneficiation facility with results of improved process efficiencies and better understanding of the phosphate flotation process.
HOW ACCURATE ARE BPL AND P205 MEASUREMENTS BY ON-STREAM MAGNETIC RESONANCE ANALYSIS?
In summary, BPL measurements for tailings are about 0.5 BPL standard error for a typical range of 2 to 8 BPL for hour-to-hour processing of phosphate matrix in
beneficiation. The figure below shows an example of data comparing BPL values from the Phospholyzer and laboratory tests on check samples.
Data for phosgypsum slurry and phosacid residue in wash water from phosacid reactor filter operation is illustrated in the below figure. Standard error
values as low as 0.1 percent P205 are attained with measurement of phosacid reaction residue
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