Control of pyrite surface chemistry in physical coal cleaning. Final report (open access)

Control of pyrite surface chemistry in physical coal cleaning. Final report

In Part I, Surface Chemistry of Coal Pyrite the mechanisms responsible for the inefficient rejection of coal pyrite were investigated using a number of experimental techniques. The test results demonstrate that the hydrophobicity of coal pyrite is related to the surface products formed during oxidation in aqueous solutions. During oxidation, a sulfur-rich surface layer is produced in near neutral pH solutions. This surface layer is composed mainly of sulfur species in the form of an iron-polysulfide along with a smaller amount of iron oxide/hydroxides. The floatability coal pyrite increases dramatically in the presence of frothers and hydrocarbon collectors. These reagents are believed to absorb on the weakly hydrophobic pyrite surfaces as a result of hydrophobic interaction forces. In Part III, Developing the Best Possible Rejection Schemes, a number of pyrite depressants were evaluated in column and conventional flotation tests. These included manganese (Mn) metal, chelating agents quinone and diethylenetriamine (DETA), and several commercially-available organic depressants. Of these, the additives which serve as reducing agents were found to be most effective. Reducing agents were used to prevent pyrite oxidation and/or remove oxidation products present on previously oxidized surfaces. These data show that Mn is a significantly stronger depressant for pyrite than …
Date: May 19, 1993
Creator: Luttrell, G. H.; Yoon, R. H. & Richardson, P. E.
Object Type: Report
System: The UNT Digital Library
Older muons are wiser: Using time information in {mu}LCR spectroscopy (open access)

Older muons are wiser: Using time information in {mu}LCR spectroscopy

For {mu}LCR with slow polarization transfer, the weak resonance signals can be strengthened by delaying the positron observation period, for pulsed and chopped muon beams. Furthermore, the sensitivity to drifts can be reduced or eliminated by using the ratios of late to early e{sup +} counts. These possibilities for using time information are discussed quantitatively.
Date: May 19, 1993
Creator: Leon, M.
Object Type: Article
System: The UNT Digital Library
A lower cost development path for heavy ion fusion (open access)

A lower cost development path for heavy ion fusion

If two features of the inertial fusion process are exploited successfully, they can lead to significantly lower costs for demonstrating the feasibility of commercial electric power production from this source of energy. First, fusion capsule ignition and burn physics is independent of reaction chamber size and hydrodynamically-equivalent capsules can be designed to perform at small yield, exactly as they do at large yield. This means that an integrated test of all power plant components and feasibility tests of various reaction chamber concepts can be done at much smaller sizes (about 1--2 m first wall radius) and much lower powers (tens of MWs) than magnetic fusion development facilities such as ITER. Second, the driver, which is the most expensive component of currently conceived IFE development facilities, can be used to support more than one experiment target chamber/reactor (simultaneously and/or sequentially). These two factors lead to lower development facility costs, modular facilities, and the planning flexibility to spread costs over time or do several things in parallel and thus shorten the total time needed for development of Inertial Fusion Energy (IFE). In this paper the authors describe the general feature of a heavy ion fusion development plan that takes advantage of upgradable …
Date: May 19, 1993
Creator: Hogan, W. J. & Meier, W. R.
Object Type: Article
System: The UNT Digital Library
Advanced, soluble hydroliquefaction and hydrotreating catalysts. Quarterly reports No. 10 and 11, January 1, 1993--May 30, 1993 (open access)

Advanced, soluble hydroliquefaction and hydrotreating catalysts. Quarterly reports No. 10 and 11, January 1, 1993--May 30, 1993

The purpose of the present program is to develop soluble analogs of surface confined catalysts that can be impregnated directly into the coal structure at low temperatures. This approach should avoid problems related to surface area dependence, a two phase (surface-liquid) reaction system and, mass transport limitations. Heteropolyanions (HPAs) offer the opportunity to develop soluble forms of surface confined catalysts. HPAs, are inexpensive, well-characterized, water soluble metal oxide clusters, e.g. [EM {sub 12}O{sub 40}]{sup 14{minus}} where E = Si or P and M = Mo or W. They are easily modified to contain other transition metals such as Co, Ni or Ru and, can be made soluble in organic solvents. The protic forms exhibit extremely high acidities pK{sub a} {approx} 0--2. In addition, selectively modified RPAs can function as low temperature hydrogenation catalysts that exhibit microporosity HPAs are multifunctional catalysts that could be used to promote both hydroliquefaction and hydrotreating. In theory, these functions could be employed sequentially or simultaneously and could permit exceptional control of liquefaction reactions and reaction conditions. Thus, the current research program involves efforts to evaluate HPAs as soluble liquefaction and hydrotreating catalysts, with the goal of developing soluble analogs of surface confined catalysts. Alternately, if …
Date: May 19, 1993
Creator: Laine, R. M. & Stoebe, T.
Object Type: Report
System: The UNT Digital Library
The use of computer vision and force sensing for tight tolerance assembly (open access)

The use of computer vision and force sensing for tight tolerance assembly

Computer vision and force control provide feedback for robot manipulation during the assembly of objects. Both techniques have weaknesses, but their complementary strengths enable them to work well together, achieving assembly with tight tolerances. For instance, camera resolution limits the accuracy of computer vision, but it can locate approximately where the part should be placed and is an excellent choice for coarse placement of the part. Force control senses the force induced by object contact and if used extensively could damage a delicate part, but when used for fine placement of an object, it compensates for the error in coarse placement. It is our goal to utilize the best features of force sensing and computer vision to reduce the error in placement of an object. The results of placing a peg in a 0.15mm tolerance hole with different camera resolutions will be presented. We have chosen to use computer vision to move the peg as close to its correct placement point as possible and force control to make minor adjustments, achieving the correct positioning of the peg.
Date: May 19, 1993
Creator: Bayliss, J. D.
Object Type: Report
System: The UNT Digital Library