An experimental investigation was carried out to improve the froth flotation method of separating coal pyrite. The effect of several surface active agents on the floatability of an Iowa coal and its associated pyrite was studied in both the presence and absence of methyl isobutyl carbinol (MIBC), a commonly used frother. The effectiveness of a special method of chemical pretreatment for depressing pyrite was also investigated. The zeta potential of the same coal and pyrite was measured under the same conditions used in the flotation tests (in the absence of frother). In the absence of MIBC, the floatability of coal and pyrite was low, and appeared to depend on pH. The maximum recovery of pyrite was obtained at a pH of 4.5 with recovery being less at higher or lower pH. The addition of a small amount of MIBC significantly increased the recovery of coal and pyrite with the increase in the recovery of coal being much greater than the increase in the recovery of pyrite. Also in the presence of MIBC, the floatability of coal and pyrite seemed to be affected more by pH than in the absence of MIBC. On the other hand, several potential pyrite depressants were …

Three investigations of difference frequency generation (DFG) of far-infrared radiation by optical mixing are described: a theory of DFG by monochromatic, focused Gaussian pump laser beams, a theory of DFG by a picosecond pump laser pulse, and an experiment using ruby-pumped dye lasers. First, the theory of far-infrared generation by optical mixing of monochromatic, focused Gaussian beams in a uniaxial crystal is developed, taking into account the effects of diffraction, absorption, double refraction, and multiple reflections and total reflection at the boundary surfaces. (Reflection and transmission coefficients of a uniaxial crystal slab are derived by a new matrix technique.) Results of numerical calculations are presented. Focusing the pump beams appreciably enhances the far-infrared output despite the strong far-infrared diffraction. In a 1-cm long crystal, the optimum focal spot size is approximately equal to or smaller than the far-infrared wavelength for output frequencies less than 100 cm{sup -1}. Double refraction of the pump beams is relatively unimportant. Both far-infrared absorption and boundary reflections have major effects on the far-infrared output and its angular distribution. The former is often the factor which limits the output power. We show that a simple model treating the nonlinear polarization as a constant lie-radius Gaussian distribution …

In model reaction systems to test amino acids in chlorinated waste effluents, several amino acids were chlorinated at high chlorine doses. (2000-4000 mg/1). Amino acids present in municipal waste effluents before and after chlorination were concentrated and purified using cation exchange and Chelex resins. After concentration and cleanup of the samples, the amino acids were derivatized by esterification of the acid functional groups and acylation of the amine groups. Identification and quantification of the amino acids and chlorination products was carried out by gas chromatography/mass spectrometry, using a digital computer data system. Analysis of the waste products revealed the presence of new carbon-chlorine bonded derivatives of the amino acid tyrosine when the effluents were treated with heavy doses of chlorine.