Fine comminution

Many analytical techniques now require very small sample sizes, for example, Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and ICP-Mass Spectrometry (ICP-MS) methods may utilise only 0.10-0.5 g of powder which must of course be representative of the original sample. Unless the collected sample is small and finely divided, representivity at this small sample size can only be achieved by fine milling the sub-samples of the coarse powder. 

Sub-micron milling is not widely used for contaminated soils however, semi-quantitative determination of asbestos may necessitate milling to submicron level. Micronising mills and other ultra-high energy centrifugal, oscillating ball mills or air jet mills are often used for this purpose. 

Preparation for X-ray diffraction studies requires micronising with minimal (preferably zero) introduction of stress to the mineral structures. For soil samples, pre-treatment to remove organic matter, soluble salts or mineral cements may be required (Buhrke etal. 1998). Productivity is typically lower than that of other milling procedures because these mills are designed to comminute only one or two samples per cycle. In addition, considerable amount of cleaning time between samples is needed to prevent cross-contamination in these small capacity mills. 

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Mortars are cements used for bonding together masonry units, such as stones or bricks. When a cement is used to conceal masonry, as a more or less smooth covering on walls, for example, it is referred to as plaster. A very fine plaster, known as stucco, is made of very thin sand or finely comminuted marble. Freshly prepared plasters and stuccos are spread on consolidated masonry to form more or less uniform and smooth layers stucco also provides a smooth and often flat outer coating. 

Preparation of Amorphous Silicon. Pertorm the experiment in a jume cupboard Mix 1 g of dry quartz sand finely comminuted in an iron mortar with 1.5 g of powdered magnesium. Spill the mixture into a test tube fastened in a clamp of a stand over a sheet of iron or asbestos. First heat the tube over its entire length, and then strongly heat its bottom. What do you observe ... 

Preparation of Potassium Chromate. (Perform one experiment on each table.) Melt a mixture of 1 g of potassium carbonate, 1 gof potassium hydroxide, and 2 g of potassium nitrate in an iron crucible by heating with the flame of a burner. While stirring the melt with an iron wire, introduce 1 g of finely comminuted chromite or -0.8 g of chromium oxide into the crucible. Roast the mixture for 5-10 minutes on a blowpipe. Treat the cooled melt with water. Filter the solution and evaporate it until a crystalline film appears. What is the composition of the formed crystals Why was potassium carbonate introduced into the reaction Write the equation of the reaction. 

Preparation of Manganese by the Aluminothermic Process. Perform the experiment in the presence of your instructor ) Put 20 g of finely comminuted manganese(IV) oxide into a porcelain crucible and roast it in a muffle or crucible furnace at 800 °G during an hour. What forms Why is manganese(IV) oxide not used directly for producing metallic manganese by the aluminothermic process ... 

Nonbanded coal consistently fine-granular coal essentially devoid of megascopic layers may be interbedded with common banded coal or form a discrete layer at the top or bottom of the seam, or may compose the entire seam formed from natural accumulations of finely comminuted plant detritus and commonly includes a significant amount and variety of remains of pollen grains, spores, planktonic algae, wax and resin granules, as well as other fragments of plants. 

Recently, the simultaneous application of pressure and elongational shear by extrusion, allows the production of elongated particles, lightly adhered to their neighbours. This produces a remarkably meatlike aligned flake structure (Cheftel et al. 1992). For fine comminutes, the adhesion occurs in the batter itself, and casings are used to form the final product shape. 

Dry lead nitrate and quartz sand in a drying cabinet at 120 °C. Assemble an apparatus as shown in Fig. 86a. Put a mixture of 70 g of finely comminuted lead nitrate and 20 g of dry quartz sand into retort 1. Fill columns 2 and 3 with phosphorus anhydride applied onto glass wool. Place thoroughly dried receiver 4 into a beaker with dry ice . Heat the retort with a strong burner flame. Give attention to how the colour of the gas changes in liquefaction. 

Carballo et al. (1996) indicated that high-pressure treatment of finely comminuted bovine meat resulted in formation of gels with smooth cohesive texture and high water retention. Ayo et al. (2005) observed that textural properties of meat batters with walnuts were not affected by high-pressure processing. However, hardness, cohesiveness, springiness, and chewiness of the cooked products were reduced by the addition of walnut. 

Meat pastes are delicately cooked meat products made primarily from meat and fat of calves and hogs and, often, from poultry (e. g. goose liver paste) or wild animal meat (hare, deer or boar). Unlike sausages, pastes contain quality meat and are free of slaughter scrapings or other inferior by-products. A portion of meat or the whole meat used is present as finely comminuted spreadable paste. 

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