Sink float procedures

Two trace element studies are being done to answer some of these questions. The first study, funded by the Environmental Protection Agency, concerns coal washing and is designed to determine the distribution of certain trace elements in coal. The various specific gravity fractions of coal are separated by a sink-float procedure. Commercially available organic fluids are used as the separation media. 

Commercially deactivated FCC Beats of varying matrix types and containing a wide range of sodium were characterized by t-plot surface area (ASTM D4365-85) to determine the effect of Na on zeolite and matrix area stability. The Beats were also examined by electron microprobe (Cameca SX50) to determine the Na distribution within a catalyst particle. Some of the Beats were separated into eight age fractions based on a modified sink/float procedure described in the literature (13,14). Bach age fraction was analyzed by ICP, t-plot and zeolite unit cell size (ASTM D3942-91). 

The same sink/float procedure can be used to remove additives, such as Davison s RV4+ vanadium trap from an Ecat sample however, since most FCC additives are much denser than FCC catalyst, this separation can usually be performed using only TBE. 

A method has been developed, utilizing sink float procedures, which calculates the H/C and N/C ratios in raw shales. In addition the technique eliminates the need for acid extraction to obtain kerogen and also estimates the H and N content of the mineral matrix. 

Test procedures for density (specific gravity) determinations are commonly too imprecise, that is, have too much of an error margin, to be employed for delicate studies of density distributions across WPCs. Those distribution charts would have been very useful for die design, for structural and functional analysis of WPC profiles, and for other research and development projects. However, by employing the sink/ float procedure for density determinations, we have been able to obtain density distribution diagrams, some examples of which are shown in Figures 6.2-69. It should be noted that the maximum density of GeoDeck WPC profiles is 1.24-1.25 g/cm. ... 

A quick and reliable method for density determination of WPC materials is a sink/float procedure. It is readily applicable in a laboratory as well as at a plant LDl Composites routinely uses this procedure for regular QC of GeoDeck deck boards at manufacturing sites. 

Fumed silica, grades, 146 In rice hulls, 145 Moisture content, 146 Natural, 146 Oil absorption, 146 Particle sizes, 146 Precipitated, 146 Specific gravity, 146 Specific surface area, 146 Synthetic, 146 Silicates, 87, 98, 123 Silicosis, 133 Mica, 133 Silylating agent, 85 Simple beam bending, 225 Single-screw compounder, 568 Sink/float procedure, 212, 216-218 Sisal fiber, 82, 86, 90, 110 Slip at the wall, 667 Slip coefficient, 211, 369-382 Slip enhancer, 381 Slip index, 376 Slip modifier, 381... 

We have studied V and Ni transport in two catalyst blends. The first blend contained 75 wt.% ECAT with 2400 ppm V and 2400 ppm Ni blended with 25 wt.% Davison RV4+ metals trap [4].The second blend contained 75 wt.% of a commercial lab-deactivated catalyst impregnated with 4900 ppm V by Davison s CPS deactivation procedure [2], mixed with 25 wt.% lab-deactivated Davison metals trap (RV4+). These catalyst blends were tested at various reactor temperatures (675-750°C), catalyst average residence times in the reactor (14 -120 min), amounts of excess oxygen (0 to 3%), and steam levels in the reactor feed (0 to 30%). Samples of 20 - 40 g of catalyst were collected and separated by the sink-float method. 

The chemical extraction procedure used to preferentially disassociate carbonate and silicate minerals is described elsewhere in this Symposium Series (12), and, thus, will be described only briefly here. The separation scheme is outlined in Figure 1. Initially, a bitumen-free oil shale is isolated by exhaustive Soxhlet extraction with a methanol/benzene mixture. A portion of the bitumen-free shale oil is then treated with HC1 to produce a carbonate-, bitumen-free oil shale. Following Soxhlet extraction with benzene/methanol to remove carbonate-associated bitunens, a portion of the carbonate-, bitumen-free oil shale is then extracted with HF/HC1 to produce a silicate-, carbonate-, bitumen-free shale. This shale is also Soxhlet extracted to remove silicate-associated bitumens. Finally, a portion of the silicate-, carbonate-, bitumen-free shale is separated by density into three fractions by sink/float techniques using both 15 wt% ZnCl2 in distilled water and pure distilled water as immersion bath media. 

Representative samples of three major bituminous coals were obtained following ASTM sampling procedures. The specific coals chosen included a northern West Virginia high volatile coal, a southern West Virginia low volatile coal, and a northern Illinois coal. Head coal samples were split out for each coal and then screen and specific gravity (sink-float) separations were made. Screen fractions produced were +1", 1x1/4", l/4"x8M, 8x28M,... 

There exist a number of familiar procedures for effecting mineral separations, including sink-float methods based on density differences and froth flotation based on wettability. Because of the tendency of kerogen to swell and soften in the presence of organic liquids and thus possibly to mobilize trapped mineral particles, and because most minerals are water-wetted and thus extractable with water, we investigated a liquid-liquid (oil-water) pelletization method. 

There are three parts in the floating/sinking samples procedure. First, it is a preparation of standard solutions with known densities. Glycerol s density is d = 1.25 g/cml If it is dilnted with water 50 50, the density of the resulting solution is, naturally, 1.125 g/cml A general formula for densities in glycerol-water systems is... 

A useful procedure for checking if test pieces lie within certain limits of density is to prepare two liquids of different but known densities to be within the known limits a test piece must sink in one liquid and float in the other. This can be employed, for example, to rapidly sort parts made in two materials which have been mixed up. A further variation6 is titration of a heavier liquid into a lighter liquid until the test piece just floats, as given in ISO 1183-16. 

The procedure we have developed to determine the VMI of a particular FCC unit involves obtaining approximately 100 grams of an FCC Beat. This Beat is first calcined in a muffle furnace at 593°C for 2 hours to remove any residual carbon. After cooling, the Beat is separated into eight fractions by a sink/fioat density separation. The density separation is performed by mixing the catalyst sample with tetrabromoethane (TBB) which has a density of 2.96 g/cc. This material is heavier than most FCC catalyst (excluding additive materials) so the catalyst sample will float in the TBB. Tetrochloroethane (TCB), which has a density of 1.58, is then added to the mixture to lower the density of the liquid and cause some of the denser catalyst particles to sink. The amount of added TCB is controlled to obtain the desired amount of sink and float fractions. 

The above procedure is repeated with each fraction until a total of eight approximately equal fractions have been obtained. The skeletal density of each fraction can be calculated based on the amount of TBE and TCE which was used to float or sink the fraction. Each fraction is submitted for ICP analysis to determine the Ni and V on each fraction and this information is used to calculate a VMI, as described below. 

In the procedure described here a method analogous to the collection of distillation cuts was employed. Ihe shale was subjected to a low specific gravity and the float fraction collected. Ihe sink fraction was subjected to an incrementally higher specific gravity and the float fraction collected. The procedure was repeated until very little material remained. In this manner a series of samples, differing primarily by organic to rock ratio, was collected. 

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