Effect of Slaking Water Temperature on Quality of Lime Slurry

There is a recent debate regarding the impact heated slaking water has on the quality of the slaked lime. This debate has caused a lot of confusion in the industry. The purpose of this paper is to clarify fact from fiction. Research has shown that in laboratory tests use of hot water for slaking will increase the temperature rise of the slaking process and reduce the size of the hydrated lime particles. ©2009 Chemco Systems

Mohamad Hassibi, Chemco Systems, L.P.

NEW MEASUREMENTS OF THE PARTICLE SIZE DISTRIBUTION OF APOLLO 11 LUNAR SOIL

Introduction
NASA initiated a major new program to determine the grain size distribution of nearly all lunar soils collected in the Apollo program. Nearly all of these studies were done by sieving the samples, usually with a working fluid such as Freon™ or water. NASA measured the particle size distribution of lunar soil 10084,2005 in water, using a Microtrac™ laser diffraction instrument. Details of their sieving technique and protocol are given in the published report.  While sieving usually produces accurate and reproducible results, it has disadvantages.
Conclusion
Direct comparison of sieve data to lightscattering data is difficult and the results must be carefully checked with standard known particle sizes and distribution. NASA analyses of NIST or NISTtraceable grain size material shows that the Microtrac results are within acceptable ranges for particle sizes between 0.33μm and ~60μm. The correspondence of the sieve data from 10084 to the light-scattering data is good and provides confidence that the two methods produce comparable results. These results open the door to future automated, rapid, and reproducible grain size analysis of planetary soils and dust. ©2009 Lunar and Planetary Science Conference

D. S. McKay (NASA Johnson Space Center), B. L. Cooper, and L. M. Riofrio (Oceaneering Space Systems)

Abstract
Most oxygen-extraction techniques are temperature-dependent, with higher temperatures resulting in higher oxygen yield. An example is hydrogen reduction, in which the optimum process temperature is 1050°C. However, glass-rich lunar soil begins to show the effects of sintering at temperatures of 900°C or lower. Sintering welds particles together due to viscous relaxation of the glass in the sample. One approach to avoid problems related to sintering, such as difficulty in removing waste material from the reactor, is to keep the soil in motion. One of several methods being studied to accomplish this is fluidized-bed processing techniques, in which the grains are kept in motion by the action of flowing reductant gas. The spent material can be removed from the chamber while still fluidized, or the fluidizing motion can continue until the material has cooled below ~500°C. Until end-to-end prototypes are built that can remove the heated soil, the most practical option is to keep the bed fluidized while cooling the waste material.
As ISRU technology advances, another option will become valuable, which is to intentionally sinter the material to a great enough extent that it becomes a brick. The free iron in lunar soil is magnetic, and ferromagnetic bricks can be manipulated by robotic systems using electromagnetic end effectors. Finally, if an electromagnetic field is applied to the soil while the brick is being formed, the brick itself will become a magnet. This property can be used to create self-aligning bricks or other building materials that do not require fasteners. Although sintering creates a challenge for early lunar surface systems, knowledge gained during prototype development will be valuable for the advanced lunar outpost. ©2007 NASA
Keywords: hydrogen reduction, fluidized bed, fluidizing, channeling, sintering, oxygen production, lunar surface systems

Bonnie L. Cooper, Robotics and Automation Group, Oceaneering Space Systems, Houston TX 77058

ENHANCED CHEMICAL REACTIVITY OF CRYSTALLINE QUARTZ BY MECHANICAL GRINDING

Summary: NASA has developed a technique for mechanically grinding crystalline silica which increases the chemical reactivity of the material as judged by the terephthalate assay. This technique uses a modern, commercially available ball mill. It provides a method for generating “fresh fractured” or “activated” silica to serve as a positive control for studies of lunar regolith chemical reactivity. The technique generates sufficient quantities of activated material (250 mg – 750 mg) to provide a ready source for biological and chemical studies. The technique may serve as a valuable method for applications with lunar regolith and other planetary materials which exhibit activation when mechanically ground.  ©2009 Lunar and Planetary Science Conference

E. Tranfield, J. C. Rask, W.T. Wallace, R. Kerschmann, D. J. Loftus.
Space Biosciences Division, NASA Ames Research Center
Habitability and Environmental Factors Division, NASA Lyndon B. Johnson Space Center

The 26 December (Boxing Day) 1997 sector collapse and debris avalanche at Soufriere Hills Volcano, Montserrat

Abstract: The southern sector of Soufriere Hills Volcano failed on 26 December 1997 (Boxing Day), after a year of disturbance culminating in a devastating eruptive episode. Sector collapse produced a c. 50 x l06m3 volcanic debris avalanche, and depressurized the interior of the lava dome, which exploded to generate a violent pyroclaslic density current. The south-directed growth of a lava lobe and build-up of lava-block talus, since early November 1997. brought the hydrothermally weakened sector to a condition of marginal stability. Limit-equilibrium stability analyses and finite-difference stress-deformation analyses, constrained by geomechanical testing of edifice and debris avalanche materials, suggest that the sector collapse was triggered by a pulse of co-seismic exogenous lava shear-lobe emplacement. Slip-surface localization was influenced by strain-weakening.

The source region fragmented into avalanche megablocks, and further disruption generated a chaotic avalanche mixture that included variably indurated and coloured hydrothermally altered material, and much talus. The avalanche consisted of several flow pulses that reflected complexities of source disruption and channel topography. In the proximal zone, within 1.5 km from source, many megablocks preserve pre-collapse stratigraphy. At major bends the avalanche separated into channelled and overspill flows. In the distal region, >2.5 km from source, stacked sets of the main lithologies occur with a hummocky surface and abrupt flowage snouts, beyond which sparse hummocks occur in a thinly spread deposit. Textures suggest emplacement by laminar mass transport of partly saturated debris riding on a frictionally sheared base. Three-dimensional numerical simulations of emplacement governed by a Coulomb-type (Pouliquen) basal friction law imply low values of friction (< 15o), consistent with geotechnical test data and the localized presence of pore-water pressures. The best-fit model suggests an emplacement time <3 minutes and a typical maximum velocity of about 40 ms-1, which are consistent with field estimates. ©2002 Geoligical Society of London

B. VOIGHT, J-C KOMOROWSKI, G. E. NORTON, A. B. BELOUSOV. M. BELOUSOVA, G. BOUDON, P. W. FRANCIS, W. FRANZ, P. HEINRICH, R. S. J. SPARKS & S. R. YOUNG

Toxicity of Lunar and Martian Dust Simulants to Alveolar Macrophages Isolated from Human Volunteers

Abstract: NASA is planning to build a habitat on the Moon and use the Moon as a stepping stone to Mars. JSC-1, an Arizona volcanic ash that has mineral properties similar to lunar soil, is used to produce lunar environments for instrument and equipment testing. NASA is concerned about potential health risks to workers exposed to these fine dusts in test facilities. The potential toxicity of JSC-1 and a Martian soil simulant (JSC-Mars-1, a Hawaiian volcanic ash) was evaluated using human alveolar macrophages (HAM) isolated from volunteers; titanium dioxide and quartz were used as reference dusts. This investigation is a prerequisite to studies of actual lunar dust. HAM were treated in vitro with these test dusts for 24 h; assays of cell viability and apoptosis showed that JSC-1 and TiO2 were comparable, and more toxic than saline control, but less toxic than quartz. HAM treated with JSC-1 or JSC-Mars 1 showed a dose-dependent increase in cytotoxicity. To elucidate the mechanism by which these dusts induce apoptosis, we investigated the involvement of the scavenger receptor (SR). Pretreatment of cells with polyinosinic acid, an SR blocker, significantly inhibited both apoptosis and necrosis. These results suggest HAM cytotoxicity may be initiated by interaction of the dust particles with SR. Besides being cytotoxic, silica is known to induce shifting of HAM phenotypes to an immune active status. The immunomodulatory effect of the simulants was investigated. Treatment of HAM with either simulant caused preferential damage to the suppressor macrophage subpopulation, leading to a net increase in the ratio of activator (RFD1+) to suppressor (RFD1+7+) macrophages, a result similar to treatment with silica. It is recommended that appropriate precautions be used to minimize exposure to these fine dusts in large-scale engineering applications. ©2007 NASA

Judith N. Latch, Raymond F. Hamilton, Jr., and Andrij Holian - Department of Internal Medicine, Division of Pulmonary and Critical Care, University of Texas Health Science Center, Houston, Texas, USA
Chiu-wing Lam and John T. James - Johnson Space Center Toxicology Group, Space Life Sciences, NASA Johnson Space Center, Houston, Texas, USA