Delwyn D. Bluhm

Frequency Dependence of the Dielectric Properties of Coal

AbstractThe dielectric properties of pulverized coal samples from identified sources were measured at 22°C over the frequency range from 1 MHz to 12 GHz and are presented graphically. Chemical composition, moisture content, bulk and particle densities, and partical distributions were also determined, Run-of-mine samples, as well as dense pyrite-bearing fractions and light fractions relatively free of pyrite, were included in the study. Dielectric constants decreased regularly with increasing frequency and were positively correlated with density. Dielectric loss factors of pyrite-bearing fractions of lower sulfur content were high at frequencies below about 50 MHz, and decreased with increasing frequency to low values at microwave frequencies. In contrast, the loss factor of a pyrite-bearing fraction with high sulfer content was low at the lower frequencies and increased with increasing frequency fo high levels at microwave frequencies. Thus, selective dielectric heating of pyrite in coal to enhance its ma...

Dielectric Heating if Mixtures Containing Coal and Pyrite

AbstractRun-of-mine (ROM) coal was separated by gravitational into fractions designated as 1.30 float (clean coal) and 2.00 sink (pyrite and ash). Dielectric properties were measured and used to predict heating rates. Predicted values suggested that pyrite and ash would heat 1.3 to 3.3 times faster than clean coal. Dielectric heating was investigated by heating mixtures containing these two fractions at 2.45 GHz Results indicated that the pyrite and ash fraction was heated from 1.9 to 2.6 times faster than clean coal

Enhanced magnetic separation of pyrite from coal after microwave heating

The objective of this research was to improve the magnetic separation of coal and pyrite by enhancing the magnetic susceptibility of pyrite in run-of-mine coal through the use of selective dielectric heating. Separation of pyrite from coal would be facilitated by changing a portion of each pyrite particle to a more magnetic form. Studies included the measurement of the dielectric properties of different coal fractions at frequencies ranging from 1 MHz to 12 GHz. These values were then used to calculate the theoretical heating expected in these materials and their mixtures at 2.45 GHz. The experimental treatment showed general agreement between theoretical and experimental heating and that it is possible to heat pyrite in coal selectively. Data indicated an increase in the apparent magnetic susceptibility of dielectrically heated pyrite samples that was roughly proportional to the time and power of treatment. Magnetic separation tests were conducted on untreated and heated coal samples. Dielectric heating produced more magnetic material in the samples, increased the magnetic susceptibility and slightly improved magnetic separations.

Measurement of texture and formability parameters with a fully automated, ultrasonic instrument

A fully automatic, ultrasonic instrument to measure texture and formability parameters on metal sheet is described. Arrays of EMAT transducers are used to transmit and receiveSo Lamb waves propagating at 0°, 45°, and 90° with respect to the rolling direction. By analyzing the frequency dependence of the phase of the received signals, the long wavelength limit of the velocities is obtained. Included is a discussion of this algorithm, and subsequent processing steps to predict the ODCsW400,W420, andW440. On steel, the prediction of drawability parametersr and Δr based on a correlation developed previously by Mould and Johnson is also discussed. Results of blind field trials at facilities of three suppliers/users of steel sheet for automotive applications and one supplier of aluminum sheet for beverage can production are reported. The former confirmed the Mould-Johnson correlation for lowr material but indicated that refinements are needed for modern steels with highr. The aluminum data suggest a correlation between W440 and the degree of four-fold earing.

Frequency Dependence of the Dielectric Properties of Coai — Part II

The dielectric properties of 18 pulverized coal samples, including run-of-mine and light and dense fractions, were measured over the frequency range from 1 MHz to 12 GHz at 22°C and are presented graphically. For Iowa coal, the dielectric loss factors of dense fractions containing most of the pyrite tended to increase noticeably as frequency increased. The loss factors of dense fractions of eastern coal (Kentucky and Ohio) tended to decrease with increasing frequency and then rose somewhat as frequency approached the microwave range. Data are also presented on the dielectric constant as a function of bulk density. Plots of the square root of the dielectric constant vs. bulk density resulted in straight lines that can be extrapolated with confidence to the coal particle density, thus providing estimates for the dielectric constant of the solid coal from measurements on pulverized samples.

Ultrasonic instrument to predict drawability of sheet metal

An ultrasonic instrument has been designed and fabricated to predict drawability of sheet metal. Using S/sub 0/ mode Lamb waves generated and detected by EMATs (electromagnetic-acoustic transducers), the instrument automatically measures ultrasonic phase delay in three directions: 0 degrees , 45 degrees , and 90 degrees with respect to the rolling direction. The delay is measured by a Fourier transform phase-versus-frequency slope algorithm applied to flash AD recorded EMAT signals. From the delays, the computer-based instrument calculates velocities and the directional Youngs modulus E(O) in the rolling plane. From the average E in the plane, a correlation curve is used to find the average plastic strain ratio, which is the drawability prediction parameter.<<ETX>>

Selective magnetic enhancement of pyrite in coal by dielectric heating at 27 and 2450 MHZ

The objective of this project is to improve the magnetic separation of coal and pyrite by enhancing the magnetic susceptibility of pyrite in run‐of‐mine (ROM) coal through the use of selective pretreatments such as dielectric heating and induction heating. Separation of pyrite from coal would be facilitated by changing a portion of each pyrite particle to a more magnetic form. The selective magnetic enhancement of pyrite in coal by dielectric heating was investigated fundamentally and experimentally. Fundamental treatment consisted by the measurement of the dielectric properties, at frequencies ranging from 1 HMz to 11.7 GHz, of a selection of coals and their pyritic fractions. These values were then used to calculate the theoretical heating that would be produced in these materials and their mixtures. The experimental treatment involved heating fractions and their mixtures at 27 and 2,450 MHz. Results showed limited agreement between theoretical and experimental heating and that it is possible to selectively heat pyrite in coal. Preliminary data indicate an increase in the apparent mass susceptibility of dielectically heated pyrite samples that is roughly proportional to the time and power of pretreatment. Magnetic separation tests are being started.The objective of this project is to improve the magnetic separation of coal and pyrite by enhancing the magnetic susceptibility of pyrite in run‐of‐mine (ROM) coal through the use of selective pretreatments such as dielectric heating and induction heating. Separation of pyrite from coal would be facilitated by changing a portion of each pyrite particle to a more magnetic form. The selective magnetic enhancement of pyrite in coal by dielectric heating was investigated fundamentally and experimentally. Fundamental treatment consisted by the measurement of the dielectric properties, at frequencies ranging from 1 HMz to 11.7 GHz, of a selection of coals and their pyritic fractions. These values were then used to calculate the theoretical heating that would be produced in these materials and their mixtures. The experimental treatment involved heating fractions and their mixtures at 27 and 2,450 MHz. Results showed limited agreement between theoretical and experimental heating and that it is possible to selecti...

Static corrosion of niobium by molten uranium-chromium eutectic☆

Abstract The results of corrosion rate tests with molten uraniumchromium eutectic (95 wt % U-5 wt % Cr) contained in solid niobium under static conditions are presented. The eutectic was capsulated in 30 mil (0.76 mm) niobium crucibles and these in turn were sealed in Inconel containers for protection from oxidation. Corrosion measurements were made after the crucibles were tested for varying lengths of time at temperatures of 900, 950 and 1000° C. Photomicrographs of the diffusion band at the interface between the solid metal and the liquid metal were used to determine the corrosion mechanism. The rates of corrosion at the three test temperatures were determined by measuring the reduction in wall thickness. The rate of corrosion was found to be temperature and time dependent. The initial rates of corrosion were found to be high and to increase with increased temperature. The rapid decrease of the corrosion rates with time was attributed primarily to the corrosion mechanism. It was concluded that under static conditions molten uranium-chromium eutectic can be contained in niobium for short-term applications.

Design and Fabrication of an Industrial-Grade Instrument to Measure Texture and Predict Drawability in Sheet Metal

Texture in sheet metal must be controlled in the rolling process to assure the fabrication properties desired in later manufacturing. Drawability is one of the required engineering properties in a family of applications including beverage cans, propane tanks, and automotive parts.