Quartz Dust Research Articles

Behaviour of advanced polymer composites in erosive/corrosive environments

The erosion/corrosion properties of the advanced polymer composites, PMR-15, BMI (Matrimid 5292) and PMR-II-20 have been studied. Specimens of these materials were exposed to jets of an erosion/corrosion medium consisting of salt, iron oxide, quartz and coarse desert dust dispersed in water. The jets impinged on the specimens perpendicular to the plane of the reinforcements for a period of approximately 2 months. The velocity of the jets was measured to be 10 m s −1. The damaged surfaces were examined both visually and under a scanning electron microscope. Damage mechanisms which are associated with this phenomenon are identified. Matrix microcracking, matrix removal and blister formation are the principal damage mechanisms observed. Deep cuts, cutting lines and rust deposition are the main features of the damaged surface. It is observed that BMI matrix composites display a large amount of matrix removal and consequently, fibre exposure. A large amount of scales of deposits are also observed. On the other hand, PMR-15 shows cutting lines, with less matrix removal than BMI. Large scale deposits are also observed on the surface of PMR-15 composite. The PMR-II composite displays the least amount of matrix removal, with brittle matrix microcracking. Blister formation is a dominant corrosive feature of the PMR-II composite.

The Effect of Suspension Medium Refractive index on the particle size analysis of quartz by laser diffraction

AbstractThe size distributions of four samples of quartz dust, suspended in liquids of different refractive index (RI), were determined using a Malvern 2600 laser particle sizing instrument. As the relative RI, between particle and suspension media, approached unity the instrument over‐estimated the mean particle size for the three finest quartz samples. An under‐estimated mean particle size was recorded for the largest quartz sample indicating the complex nature of light scattering by small particles under conditions of low relative RI.A regime of relative refractive index is determined within which particle size analysis using laser diffraction, invoking anomalous diffraction theory, becomes prone to large errors and this range is compared with the van de Hulst criterion.

Soviet equipment for production of polymer-impregnated concrete articles

Based on the foreign and domestic experience of work with polymer-impregnated concrete, a set of essential technological and engineering documentation has been prepared for the production of various items using highly filled polymer resins. In this paper brief information is given on the technology and equipment for the production of decorative tiles (DT) and sanitary hardware (SH).* The DT and SH manufacturing process includes: filler preparation [making working powder mixture (WPM) with a fixed granulometric composition and moisture content]; resin preparation for mixing with a dye of the fundamental tone and some other additives which increase the stability of the properties of the articles, impart degassing properties, and so on; preparation of a composition for transparent face coat of the article (gel coat); mixing the resin with a hardener, an accelerator, and, if necessary, with'styrene and aerosol for imparting the properties of a Bingham fluid with a fixed ultimate shear stress that prevents the inleakage phenomenon when a coat is applied; dye preparation (drying, screening, etc.); mold preparation (cleaning, application of a separating layer on the working surface to prevent sticking of the polymer-impregnated concrete to the mold at the time of pouring and hardening, application of a partially hardened gel coat); mixing all ingredients of the polymer-impregnated concrete and pouring into the mold; hardening of the filled composition, mold dismantling, and withdrawal of the articles; seam removal, necessary mechanical finishing (for instance, drilling holes), and packaging. DT and SH can be produced by using unsaturated polyester resin, hardener, and accelerator (cobalt naphthenate, methyl ethyl ketone peroxide, and isopropyl benzene hydroperoxide), filler (marble powder, molding sand, ground quartz dust, etc.), aerosol, mineral pigments (chromium oxide, titania, iron oxide yellow or red pigment, etc.). Methylene chloride and acetone are used as additional materials for cleaning the surface and the waxbased separating grease of a complex composition. The polymer-impregnated concrete articles have the following characteristics: bulk density 2200-2430 kg/m 3, compression strength 70 MPa, tensile strength 7-9 MPa, impact strength 0.2-0.25 J/cm 2, water absorption (in 24 h) 0.05-0.1%, wearability 0.015-0.025 g/cm z . Organizationally and technically the production was based on independent modules: WPM preparation module with 12,500 ton/yr (2.5 ton/h) capacity and module for preparation of resin, gel coat, pigments and additives, and separating crease. These modules allow DT and SH manufacture for 30,000 bathroom units and up to i00,000 mZ/yr. Production and repair of molds are an independent section. The DT molding section is also designed as a module, but with a capacity of I0,000 bathroom units; the SH molding section provides for production of I00,000 m2/yr. The plant has also a section for mechanical finishing and packaging and is provided with a system of air cleaning from styrene. Thus, the plant capacity varies, depending on the degree of completion, from I0,000 to 30,000 units. Mixtures of marble powder or quartz sand 0-i00, 400-800, and 1000-2500 ~m in size, containing not more than 0.5% moisture, is used as fillers. The production line for WPM preparation includes a feeding unit with a receiving bin and a conveyer for delivery of the raw material for treatment, a screen for separating particles of an unscheduled size and other inclusions, a jaw or cone crusher (for lump marble), a drum dryer, a multistage screen for separating the material into two working size fractions and fine residues which, along with a part of the large fraction, is delivered for grinding, a vibratory mill for

Chirality of quartz. Fibrosis and tumour development in dust inoculated mice

Dextro (d) and laevo (l) forms of quartz dust was inoculated intranasally and subcutaneously into 2-month-old (C57 x BALB/c)F1 mice which were killed 18 months later. Both d and l quartz caused fibrosis, liver nodule formation and an enhanced incidence of lymphoma/leukemia. However, the tumour incidence was significantly higher in l than in d quartz dust-treated animals. It is concluded that in addition to effects clearly independent of chirality there is evidence that the biological response to nonidentical mirror images of solid crystals may differ.

Zymosan-induced chemiluminescence of alveolar macrophages: Depression by inorganic dust constituents

A method has been developed which allows the incubation of alveolar macrophages as weakly affixed monolayers in siliconized glass dishes. Without vigorous mechanical agitation and without using proteolytic enzymes, these cells were subsequently transferred to cuvettes where the zymosan-stimulated chemiluminescence of the suspended cells was measured. In vitro incubations of activated rabbit alveolar macrophage monolayers with airborne dusts from four West German sites (1 to 200 micrograms/10(6) cells), fly ash fractions of a special waste incinerator at Hamburg (50 to 1,000 micrograms/10(6) cells), and quartz dust DQ 12 (5 to 200 micrograms/10(6) cells) resulted in a dose- dependent depression of the zymosan-stimulated chemiluminescence. The depression of chemiluminescence was correlated with particle numbers, estimated dust surface, and antimony and lead masses of the dusts to which the cells were exposed. Cytotoxicity was better correlated with these parameters than with dust mass.

Preparation of quartz dust on filter samples for a proficiency testing scheme

A technique has been developed for the production of batches of membranefilters loaded with respirable quartz dust to a high degree of precision by mass. The quartz dust was sampled by an array of personal sampling cyclones fitted with membrane filters. This technique produces filters which resemble samples obtained in the workplace and is suitable for the manufacture of reference samples for a proficiency testing scheme.

Subchronic inhalation toxicity of amorphous silicas and quartz dust in rats

The inhalation toxicity of three amorphous silicas (Aerosil 200, Aerosil R 974 and Sipernat 22S) was compared with that of quartz dust. Rats were exposed to 1, 6 or 30 mg Aerosil 200/m 3, 30 mg Aerosil R 974/m 3, 30 mg Sipernat 22S/m 3 or 60 mg quartz/m 3 for 6 hr/day, 5 days/wk for 13 wk. Some rats were killed at the end of the exposure period and some were killed 13, 26, 39 or 52 wk after the end of exposure. Clinical signs, body weight, haematology, biochemistry, urinalyses, organ weights, retention of test material in the lungs and regional lymph nodes, collagen content of the lungs, and gross and microscopic pathology were determined in order to disclose possible adverse effects and to study the reversibility, stability or progression of the effects. All test materials induced increases in lung weight, and pulmonary lesions such as accumulation of alveolar macrophages, inflammation, alveolar bronchiolization and fibrosis. In addition, rats exposed to Aerosil 200, Aerosil R 974 or quartz developed granulomatous lesions. Silicosis was observed only in quartz-exposed animals. At the end of the exposure period, Aerosil 200 and quartz had induced the most severe changes. Quartz dust was hardly cleared from the lungs and the changes in the lungs progressed during the post-treatment period, and eventually resulted in lesions resembling silicotic nodules and in one squamous cell carcinoma. Although Aerosil 200 was very quickly cleared from the lungs and regional lymph nodes, the changes in these organs were only partly reversed during the post-exposure period in rats exposed to 30 mg/m 3. Aerosil R 974 and the lower levels of Aerosil 200 resulted in less severe, and mostly reversible, changes. The slightest changes were found after exposure to Sipernat 22S, notwithstanding the persistence of this silica in the lungs during the major part of the post-treatment period. The results of this study revealed that only quartz induced progressive lesions in the lungs resembling silicotic nodules. Of the amorphous silicas examined Aerosil 200 induced the most severe changes in the lungs, which only partly recovered, whereas Sipernat 22S induced the least severe, completely reversible lung changes.

Hydrophilic and hydrophobic sites on dehydrated crystalline and amorphous silicas

Surface dehydroxylation of amorphous and crystalline silicas (quartz dust) has been investigated from the standpoint of the development of hydrophobicity upon thermal treatment. Hydrophobicity occurs when only siloxane bridges and isolated silanols (IR band at ca. 3750 cm–1) are present and is monitored by an enthalpy of adsorption of water lower than the latent heat of liquefaction (44 kJ mol–1). This calorimetric method allows the evaluation of the extent of hydrophilic and hydrophobic patches when both are present at the surface. All silicas develop hydrophobicity upon thermal treatment in vacuo, but quartz is much less easily dehydroxylated than amorphous materials. It is still mainly hydrophilic after outgassing at 1073 K, whereas pyrogenic silicas (Aerosil) become hydrophobic upon outgassing at T < 673 K. Quartz is also characterized by a few very reactive sites (q 90 kJ mol–1), absent on the amorphous specimens. Both these facts might be related to the specific quartz pathogenicity. Rehydroxylation at room temperature of dehydroxylated silicas occurs to a very limited extent. Hydrophilic patches exhibit a marked heterogeneity towards water with an enthalpy of adsorption decreasing from 90 to 44 kJ mol–1. The enthalpy of adsorption approaches 44 kJ mol–1 corresponding to the addition of multilayers of adsorbed water.

A method of detecting tubercle bacilli in sputum

Tubercle bacilli were injected intravenously to mice after dusts were injected into their subcutaneous tissue. Out of 23 kinds of dusts tested, a quartz dust enhanced most the growth of mycobacteria injected intravenously in mice. Based on this a mixture of the sputum from patients with pulmonary tuberculosis and finely powdered crystalline silica was inoculated subcutaneously into the flanks of mice. Growth of tubercle bacilli was demonstrated occasionally for the sputum specimens from smear-positive and culture-negative cases, and even for smear- and culture negative cases. When a sputum specimen which yielded many colonies on routine egg medium were tested, the growth of bacteria became visible as early as 2 weeks after inoculation. On the other hand, it took 3 to 4 weeks for the visible growth of bacilli, when a sputum specimen yielded only a few or no colonies on culture medium. In this method, the bacilli appeared earlier and more frequently than in the routine culture method on egg medium. Thus an inoculation into mice with a mixture of the sputum and quartz powder was shown to be a sensitive method for the diagnosis of pulmonary tuberculosis.

気体サイクロンの５０％分離粒子径について （第３報） 新公式によるカット粒子径と平衡粒子径との関係

In order to make certain of the validity of the expression for 50% separation diameter dc presented in my 2nd report, the theoretical values of dc were compared with the values of “equilibrium particle size” dR=E which can be derived from the experimental values of collection efficiency E in 4 similar cyclones for talc powder separation. Similarly, comparison between the theoreticals dc and the experlmentals dR=E are also made in the case of quartz dust separation in a cyclone with vortex arrestor in the dust outlet.It is found that the values of the cut size ratio, dR=E/dc, could be expressed as follows:dR=E/dc=K/Rec0.1where K is constant value dependent on introduced cyclone including the effects of agglomeralion, bouncing or re-entrainment of particles upon the overall efficiency: and Rec is the Reynolds Number based on the cut size particle expressed asRec=dcws/vuk2/grk

Effect of immunoglobulins on mineral dust-induced production of reactive oxygen metabolites by human macrophages

Mineral dust-induced production of reactive oxygen metabolites (ROMs) by human monocyte-derived macrophages was investigated using lucigenin-dependent chemiluminescence. Chrysotile asbestos alone caused only weak ROM production by macrophages, but the addition of polyclonal immunoglobulin enhanced the reaction strongly. The phenomenon was seen with 1-, 4-, and 7-day-old cell cultures. Polyclonal immunoglobulin also slightly enhanced the ROM responses induced by amosite, crocidolite, and quartz dust. The enhancing effect could be achieved with several monoclonal immunoglobulins (isolated from the sera of myeloma patients), but IgA and IgG had the strongest effects. We suggest that immunoglobulins may interact with mineral dusts in a "nonimmunological," antigen-independent way and that the so-formed dust-immunoglobulin complexes may amplify the production of ROMs by inflammatory cells. This may explain a number of in vivo phenomena in which immune responses (for instance hypergammaglobulinemia and the presence of autoantibodies) have been shown to relate to the progression of mineral dust-induced pulmonary disease.

Effect of mineral dust on generation of superoxide radicals and hydrogen peroxide by alveolar macrophages, granulocytes, and monocytes

Phagocytosis of quartz dust by alveolar macrophages and monocytes of rabbits and human monocytes and granulocytes is accompanied by stimulation of substrateless recovery of nitroblue tetrazolium to formazan. It reflects activation of oxygen-dependent bactericidal phagocyte system and generation of active oxygen forms. Less fibrogenic and cytotoxic dust of aluminium oxide increased formazan formation insignificantly. Extracellular generation of superoxide radicals and hydrogen peroxide was not discovered during phagocytosis of quartz by alveolar macrophages and monocytes. Incubation of human granulocytes with silica caused, on contrary, considerable increase in exogenous generation of superoxide radicals and hydrogen peroxide. Less fibrogenic dust of aluminium oxide under the conditions had no effect on generation of hydrogen peroxide and induced acute decrease in generation of superoxide radicals by granulocytes. The obtained results testify both to the essential part of active oxygen form during pathologic processes with pneumoconiosis, and also to a great similarity among biochemical processes, characterizing interaction of alveolar macrophages and monocytes with mineral dust.

DUST CONTROL MEASURES IN DUTCH BRICKWORKS

Dust concentrations in Dutch brickworks and the efficiency of measures to reduce exposure to dust were investigated in four representative works. The project consisted of three parts. In Part 1 total and respirable dust and respirable quartz dust were measured before control measures were recommended or taken. The dust concentrations were in many cases too high; the respirable quartz dust concentration was most critical. Recommendations were made for the introduction at short notice of simple control measures and good housekeeping rules. The works were investigated again a year later to assess the effect of the recommendations (Part 2). The concentrations had decreased considerably in some cases where the recommendations were followed. Part 3 describes the experiment with nozzles that generate a fine water mist to moisten dusty surfaces and so reduce dust levels. These nozzles reduced respirable dust concentrations to 0.5 mg m−3 or less, which is acceptable.

Depression of alveolar macrophage hydrogen peroxide and superoxide anion release by mineral dusts: Correlation with antimony, lead, and arsenic contents

Activated rabbit alveolar macrophages were incubated with airborne dusts from four West German sites (1 to 200 micrograms/10(6) cells) and waste incinerator fly ash fractions (50 to 500 micrograms/10(6) cells). Quartz dust DQ 12 (5 to 200 micrograms/10(6) cells) and Fe2O3 (0.05 to 50 micrograms/10(6) cells) were used as control dusts. The zymosan-stimulated hydrogen peroxide and superoxide anion release of the macrophages were not affected significantly by Fe2O3. All other investigated dusts decreased the two cell functions which were correlated negatively with surfaces, particle numbers, and antimony, lead, and arsenic contents of the dusts. The influence of heavy metal antagonisms and dust surfaces on dust toxicity against alveolar macrophages is discussed.

Oxidized proteins in the bronchoalveolar lavage fluid of monkeys exposed to hyperbaric atmosphere and/or quartz dust

Oxidized proteins in the bronchoalveolar lavage fluid of monkeys exposed to hyperbaric atmosphere and/or quartz dust

Quartz-dust-induced production of reactive oxygen metabolites by human granulocytes

We studied the effect of quartz on the production of reactive oxygen species by human polymorphonuclear leukocytes (PMN) in vitro by a chemiluminescence (CL) assay. Quartz caused a rapid dose-dependent CL response in the cells. Diamond dust used as an inert control did not stimulate the production of reactive oxygen metabolite by PMN. The quartz-induced activation of oxygen metabolism was also demonstrated by measuring oxygen consumption, nitroblue tetrazolium reduction, and superoxide and hydrogen peroxide production by PMN. Poly-vinyl-pyridine N-oxide (a quartz surface modifying agent) completely abolished the quartz-induced response, but had no effect on opsonized zymosan-induced CL response of PMN. The effect of N-acetylcysteine (a known antioxidant) was inhibitory to the CL formation induced by both quartz and opsonized zymosan. Our results are in agreement with the hypothesis that quartz-induced production of reactive oxygen metabolites is a possible mechanism by which quartz dust produces chronic inflammation and tissue injury of the lung. Agents interfering with the generation of reactive oxygen metabolites may provide a rationale for treatment of mineral-dust-induced pulmonary disease.

Silica exposure and silicosis among Ontario hardrock miners: III. Analysis and risk estimates.

An epidemiological investigation was undertaken to determine the relationship between silicosis in hardrock miners in Ontario and cumulative exposure to silica (free crystalline silica--alpha quartz) dust. This report describes the analytic method and presents the risk estimates.

Silica exposure and silicosis among Ontario hardrock miners: II. Exposure estimates.

An epidemiological investigation was carried out to determine the relationship between silicosis in hardrock miners in Ontario and cumulative exposure to silica (free crystalline silica--alpha quartz) dust. This second report describes a side-by-side air-sampling program used to derive a konimeter/gravimetric silica conversion curve. A total of 2,360 filter samples and 90,000 konimeter samples were taken over 2 years in two mines representing the ore types gold and uranium, both in existing conditions as well as in an experimental stope in which dry drilling was used to simulate the high dust conditions of the past. The method of calculating cumulative respirable silica exposure indices for each miner is reported.

Silica exposure and silicosis among Ontario hardrock miners: I. Methodology.

An epidemiological investigation was undertaken to determine the relationship between silicosis in hardrock miners in Ontario and cumulative exposure to silica (crystalline silica--alpha quartz) dust. This first report describes the cohort, the method of classifying the radiographs, and the identification of a case of silicosis.

Averaged emissivities of quartz and sahara dust powders in the infrared region

The averaged emissivities over the wavelength regions or the specified zenith angles may be useful as an input data for model surface characteristics. However as shown in the paper by Takashima and Masuda (1987), emissivities ϵ of quartz and Sahara dust powders exhibit strong wavelength dependence in the infrared region (7–17 μm). Furthermore, ϵ depends upon their particle sizes and zenith angles as well. Thus these values would not numerically be estimated by Figs. 4 and 5 in their paper. Therefore, an additional computation of the averaged emissivities was undertaken in the regions, 600–1400, 760–1240, 880–940, and 800–860 cm −1. The region 760–1240 cm −1 includes that of the maximum earth thermal radiation, whereas the regions 880–940 and 800–860 cm −1, correspond to NOAA-AVHRR infrared window channels.