187,201 research outputs found
Water-bentonite interaction in balling of iron ores
No full textThe growth of granules in batch agglomeration of hematite iron ore powder with or without the presence of bentonite additive can be described by the non-random coalescence mechanism. The specific balling rate constant in the kinetic expression for median ball-size increases with increasing water content of the feed and decreases with addition of bentonite. It is suggested that, in so far as the gross kinetic behaviour is concerned, the role of bentonite in balling is to immobilize a fraction of the water present in the charge. The amount of bound water has been estimated from the balling rate constant data and the extent of immobilized water is found to be disproportionately higher for wetter feeds. Implications of these results in operation and control of industrial iron ore balling circuit are discussed
Federal Vessels Driving Back the Iron-Plated Rebel Steamer Yorktown, which At mpted to Run the Blockade, Near Newport News
No full textPublished engraving based upon DRWG/US - Balling, no. 1 (A size).Attributed to Balling in New York Illustrated News caption.Title printed below image.Initials T.N. engraved lower right of image indicate that Thomas Nast prepared the wood engraving for publication.Published in: New York Illustrated News, 30 September 1861, p. 337.Source unknown
Investigation of Balling Characteristics of Mixture of Iron Oxide Bearing Wastes and Iron Ore Concentrates
Get PDFIron oxide bearing wastes in form of dust and sludges are hard to handle because of their micron size particles and moisture content in case of sludge. More often they are stockpiled in large quantities that can occupy large area of real and agricultural estates and cause pollution. Balling or palettization, an agglomeration process was used to process the wastes in order to address the problem of micron size particles and to make them fit for recycling back into metallic iron production route like blast furnace. Balling or green pelletization is the process of forming nearly
spherical shaped granules by tumbling moistened particulates with or without binders in balling drums or discs disc. For a pellet to be effective either for being transported or for being recycled in blast furnace to produce metallic iron without disintegrating to dust its balling characteristics should measure up to required standard. Most outstanding of those balling characteristics include Drop Number, Green or Wet Compression Strength, Dry Compression Strength, Abrasion and Tumbler Indices. In this work iron oxide bearing wastes was mixed with iron ore concentrates in various proportions. These mixes were taken through balling or wet pelletization process using Radicon Balling Disc. The balls formed balls were taken through Drop number tests adopting the Free Fall
method, where balls are made to fall freely from a height of 50 mm on steel surface, Green compression and Dry compression tests using a 5 kN Universal Testing Machine (INSTRON Corp., model 1011 UK) System while Abrasion and Tumbler indices tests were conducted using Tumbler
Index cylinder or drum and adopting ASTM method. It was found that Drop number as high as 7.8 times, Green compression strength and Dry compression strength up to 11.7 N/pellet and 25.99 N/pellet respectively were attained by some of the pellets. The Tumbler and Abrasion indices
recorded were up to above 95% and 5% respectively. These values are higher than the minimum recommende
Balling and granulation kinetics revisited
Get PDFBalling of finely comminuted solids by random coalescence and granulation of iron ore fines and other minerals by autolayering are two major size enlargement processes. The existing kinetic model for random coalescence does not take into account the strong dependence of coordination number on the size distribution of agglomerating entities. We present a coordination number based coalescence model, which mimics the underlying physical process more realistically. Simulations show that in spite of highly diverse model structures, random and coordination coalescence models give remarkably similar results. Only static models of autolayering are available presently. These map the input size distribution of feed solids into steady state or terminal size distribution of granules, with little or no information on the path traversed by the process. We propose a continuous-time dynamic model of autolayering within the population balance framework. The model, which is based on the proportionate growth postulate of autolayering, agrees reasonably well with experimental data
Reliability Assessment on the Re-Balling of PBGA from SnPb to Pb-Free Solder Spheres
No full textDue to environmental consciousness and legislative regulations, lead-free solders will soon replace most of conventional lead-containing solders in microelectronic industry. However, it is an evident loss or waste to abandon these Pb-containing devices directly. This paper describes a new re-balling method to replace SnPb by leadfree solder ball on BGA packages. After re-balling process, no Pb was detected in the solder balls by using EDX. Compared to as-reflow SnAgCu solder balls without the re-balling, no significant degradation of ball attachment strength was found on re-balled specimens. This paper discusses the effect of thermal aging at 150°C on the ball attachment strength with and without re-balling. The strength of solder balls is investigated by ball shear and cold bump pull (CBP) tests. The test configuration and the experimental data are reported in detail. The test results indicate that the ball attachment strength of reballed balls after thermal aging is similar as the results without re-balling.</p
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Composite powder consolidation using selective laser melting:Input energy/porosity morphology/balling effect relation
No full textIn this study AlSi10 Mg/Al2O3 composite was processed via selective laser melting. The influence of different process parameters namely, laser power, scan speed and hatch spacing was investigated to determine their effect on the physical and mechanical properties of the consolidated powders. Input energy and balling effect, had a major influence on the developed pore morphology. Poor consolidation associated with poor heat diffusion and insufficient melting occurred at the low input energy. Intermediate input energy resulted in the formation of continuous porosity along the building direction separated by consolidated zones of equal width and associated with uniform balling effect. High input energy developed distorted porosity with non-uniform distribution associated with irregular course balling. The formed continuous porosity is attributed to the segregation and migration of alumina particles to the spacing between the deposited successive powder layers followed by their selective melting forming oxide films that acts as a barrier to the complete solidification.</p
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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