Carrier Flotation of Hematite

The production of fine materials is unavoidable during the comminution of iron ore. Due to the difficulty of recovering iron from this fine material by various gravity separation methods, flotation can often be a more attractive process producing high-grade material at high recovery. One variation of the flotation process, that can be useful for recovering ultrafine minerals (<10 mm), is known as carrier flotation. This process involves the utilization of coarse particles (> 150 mm) which act as flocculation centres to which the fine hematite particles (10-40 mm) become attached and are carried or “piggy-backed” into the froth phase.

Aggregation mechanisms are important interactions between particles in a flotation process. These interactions may include hetero-aggregation (i.e. occurring between particles of different minerals and size), mutual aggregation (i.e. occurring between particles of the same mineral and size) and selective aggregation (i.e. occurring between coarse carrier particles and the fine particles of one mineral in a mixture). Selective aggregation can be considered the same as mutual aggregation when the carrier and desired mineral are the same.

The objective of this paper is to demonstrate that carrier flotation is a significant phenomenon in the flotation of hematite fines using oleic acid as a collector.       

ВАРІАНТ V

Technological Trends in Mining

       In step with industrial and technical advances the tempo of mining activity has accelerated rapidly.

   Shallow mines containing high-grade ore deposits either have been or are being rapidly mined out and their place can only be taken by deposits lying at minerals greater depths.

   Scientists consider that the nature and characteristics of individual minerals al deposits will not differ greatly, except i minerals n the matter of average depth from those of today.

   Though more and more useful in the world are mined by open-pit mining, the importance of underground mining is still great because the average grade of ore m minerals underground is higher than that of open-pit ore.

   In mining deeper and lower grade deposits there is a tendency to use in situ mining which seems to be a promising process and the one on which research is concentrated on the international scene.

   Another problem of mining is further mechanization and automation of mining process. Thus, in underground mining great attention is paid to designing efficient winning complexes consisting of self-moving powered supports incorporated with shearer or plough operating in productive faces.

   It is of interest to note that computers have become valuable tools in many mining applications. They are especially useful in mine design, ventilation, simulation, monitoring, and in other fields. The computer software deals with information on seam thickness, borehole data, the nature of disturbances, faulting and folding and other details. Computers can help determine production levels of different extraction strategies, carry out mine planning. Microcomputers also find more wider use in mining and exploration projects.

   Special attention is paid to mine safety as part of mechanization and automation of mining processes. Automatic instruments and systems along with safety devices effectively monitor the working environment and ensure human safety in all mining operations.

   The mining industry today is to continue to satisfy the world’s rapidly growing demands for minerals and metals. To meet this challenge the most important requirement is the efficient use of modern machinery and human resources based on scientific and technological progress.

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ВАРІАНТ I

Architecture

   Architecture is the art and science of designing buildings and other physical structures. A wider definition often includes the design of the total built environment, from the macro-level of how a building integrates with its surrounding manmade landscape (see town planning, urban design, and landscape architecture) to the micro-level of architectural or construction details and, sometimes, furniture. The term "Architecture" is also used for the profession of providing architectural services.

   Architects are primarily driven by the creative manipulation of mass, space, volume, texture, light, shadow,materials, program, and pragmatic elements such as cost, construction and technology, in order to achieve an end which is aesthetic, functional and often artistic. This distinguishes architecturefrom engineering design, which is driven primarily by the creative manipulation of materials and forms using mathematical and scientific principles.

   Separate from the design process, architecture is also experienced through the senses, which therefore gives rise to aural, visual, olfactory, and tactile architecture. As people move through a space, architecture is experienced as a time sequence. Even though our culture considers architecture to be a visual experience, the other senses play a role in how we experience both natural and built environments.Attitudes towards the senses depend on culture. The design process and the sensory experience of a space are distinctly separate views, each with its own language and assumptions.

   Architectural works are perceived as cultural and political symbols and works of art. Historical civilizations are often known primarily through their architectural achievements. Such buildingsas the pyramids of Egypt and the Roman Coliseum are cultural symbols, and are an important link in public consciousness, even when scholars have discovered much about a past civilization through other means. Cities, regions and cultures continue to identify themselves with andareknown by their architectural monuments

ВАРІАНТ II

The Architect

   Architecture as a profession is the practice of providing architectural services. The practice of architecture includes the planning, designing and oversight of a building's construction by an architect. Architectural services typically address both feasibility and cost for the builder, as well as function and aesthetics for the user.

   Architecture did not start to become professionalized until the late nineteenth century. Before then, architects had ateliers and architectural education varied, from a more formal training as at the Ecole des Beaux-Arts in France, which was founded in the mid seventeenth century, to the more informal system where students worked in an atelier until they could become independent. There were also so-called gentlemen architects, which were architects with private means. This was a tradition particularly strong in England during the eighteenth and nineteenth centuries. Lord Burlington, designer of Cheswick House, (1723-49) is an example. Some architects were also sculptors, such as Bernini, theater designers such as Filippo Juvarra and John Vanbrugh, and painters, such as Michelangelo and Le Corbusier.

   In the 1440s, the Florentine architect, Albert, wrote his De Re Aedificatoria, published in 1485, a year before the first edition of Vitruvius, with which he was already familiar. Albert gives the earliest definition of the role of the architect. The architect is to be concerned firstly with the construction. This encompasses all the practical matters of site, of materials and their limitations and of human capability. The second concern is "articulation"; the building must work and must please and suit the needs of those who use it. The third concern of the architect is aesthetics, both of proportion and of ornament.

   The role of the architect is constantly evolving, and is central to the design and implementation of the environments in which people live. In order to obtain the skills and knowledge required to design, plan and oversee a diverse range of projects, architects must go through extensive formal education, coupled with a requisite amount of professional practice.

   The work of an architect is an interdisciplinary field, drawing upon mathematics, science, art, technology, social sciences, politics and history, and often governed by the architect's personal approach or philosophy. Vitruvius, the earliest known architectural theorist, states: "Architecture is a science, arising out of many other sciences, and adorned with much and varied learning: by the help of which a judgment is formed of those works which are the result of other arts." He adds that an architect should be well versed in other fields of learning such as music and astronomy. Vitruvius' broad definition of the architect still holds true to some extent today, even though business concerns and the computer have reshaped the activities and definition of the modern architect in significant ways. 

ВАРІАНТ III