Coal Tar Pitch

Coal Tar Pitch  Coal tar pitch, derived from by-product coke ovens, is the preferred material for use as a binder in the manufacture of carbon and graphite electrodes. Coal tar pitch is a coal conversion product. Its IUPAC name is ‘Coal Tar Pitch, High temperature”. Its CAS number is 65996-32-2 and EINECS number is 266-028-2. It is the shiny, dark-brown to black residue produced by distillation of coal tar. Coal tar pitch contains a large number of substances. It is solid at room temperature and consists of a complex mixture of numerous polycyclic aromatic hydrocarbons (PAHs), their methyl and polymethyl derivatives, and heterocyclics, and shows a broad softening range instead of a defined melting temperature. The hydrogen (H2) aromaticity of coal tar pitch (ratio of aromatic to total content of H2 atoms) varies from 0.7 to 0.9. Production of coal tar pitch Coal tar pitch is currently produced from coal tar, which is a byproduct of high temperature coking of coal in the manufacture of metallurgical coke. The tar predominantly contains a mixture of bi- and poly-condensed aromatic hydrocarbons and also compounds with heteroatoms in rings (predominantly nitrogen bases from the quinoline and acridine series, 1 % to 2 %) and phenols (1 % to 2 %). Upon distillation, 8 % to 12 % of a naphthalene fraction, 5 % to 9 % of an absorption fraction, and 21 % to 26 % of an anthracene fraction, which boiled away to 360 deg ?, are separated. The residual part of the tar is the pitch which contains nonvolatile and low volatile substances, whose average yield is around 2 % of the coking coal charge used for high temperature carbonizing. The industrial production of coal tar pitch consists of the fractional distillation of the coal...

Employees and organizational responsibility...

Employees and organizational responsibility Employees, whether unskilled or skilled, manual, clerical, or knowledge worker, are required to take the burden of responsibility. For this, they need tools, incentives, and security. Organizational management normally expects every employee to be responsible and has focus on his job. The job has to make achievement possible. Though the job is not everything, yet it comes first. If other aspects of working are not satisfactory, they can spoil even the most achieving job. But if the job itself is not achieving, nothing else can provide achievement. This may appear to be silly, but the major approaches to managing the employee, throughout history, have focused on elements external to the job. For instance, several trade union leaders, while focusing on ownership, have, by and large, left unchanged the structure of jobs and the traditional practices of managing employees. Protectiveness focuses on welfare, i.e., on things like housing and health care etc.. These are very important, but not substitutes for job achievement. More recent solutions such as the ‘co-determination’, which certain trade unions are pushing to put union representatives on the board of directors and into top management but do not concern themselves with the employees’ job itself. The fundamental reality for every employee is the eight hours or so he spends on the job. It is this job, through which the great majority of the employees have access to achievement, to fulfillment, and to the organizational success. To enable the employee to achieve, he must therefore first be able to take responsibility for his job. This basically needs (i) productive work, (ii) feedback information, and (iii) continuous learning (Fig 1). Fig 1 Basic needs of employees for taking responsibilities It is foolish to ask employees to take responsibility for their...

Coal Tar and its Distillation Processes Dec26

Coal Tar and its Distillation Processes...

Coal Tar and its Distillation Processes Coal tar, also known as crude tar, is the by-product generated during the high temperature carbonizing of coking coal for the production of the metallurgical coke in the by-product coke ovens. It is a black, viscous, sometimes semi-solid, fluid of peculiar smell, which is condensed together with aqueous ‘gas-liquor’ (ammoniacal liquor), when the volatile products of the carbonization of coking coal are cooled down. It is acidic in nature and is water insoluble. It is composed primarily of a complex mixture of condensed-ring aromatic hydrocarbons. It can contain phenolic compounds, aromatic nitrogen (N2) bases and their alkyl derivatives, and paraffinic and olefinic hydrocarbons. In the process of coal carbonization the constituents of the tar escape from the coke ovens in the form of vapour, with a little solid free carbon (C) in an extremely finely divided state. The tar is precipitated in the hydraulic main, in the condensers, and scrubbers etc., in a liquid state, at the same time as the ammoniacal liquor is formed. The tar formed in the hydraulic main is, of course, poorer in the more volatile products than that formed in the condensers and scrubbers, and is consequently much thicker than the latter. The normal yield of coal tar during the coal carbonizing process is around 4 %. Coal tar has a specific gravity normally in the range of 1.12 to 1.20, but exceptionally it can go upto 1.25. It depends on the temperature of carbonization. The lower specific gravity tars are generally produced when low carbonization temperatures are used. Viscosity of tar affected similarly. The heavier tars contain lesser benzol than the lighter tars, and more fixed carbon. The nature of the raw material and the temperature of carbonization affect the chemical composition,...

Coal Ash

Coal Ash Coal ash is the mineral matter present in the coal. It is a waste which is left after coal is combusted (burned). It is the particulate material which remains after coal is burned. It includes fly ash (fine powdery particles which are carried up the smoke stack and captured by pollution control devices) as well as coarser materials which fall to the bottom of the furnace. It has different physical and chemical properties depending on the geochemical properties of the coal being used and how that coal is burned. Coal ash is also referred to as coal combustion residuals. It has very little organic fraction. Chemical constituents of coal ash may include nitrogen (N2), sulphur (S), unburned carbon (C), heavy metals, radioactive elements, and polycyclic aromatic hydrocarbons (PAHs). Coal ash also contains coarse particles and fine particles which can be inhaled and may contribute to public health and environmental problems. Coal ash contains many toxic contaminants. When coal ash spills, leaks or leaches into nearby ground water or waterways, the toxins contained within pose serious health risks to nearby communities. Depending on where the coal was mined, coal ash typically contains heavy metals including arsenic, lead, mercury, cadmium, chromium and selenium, as well as aluminum, antimony, barium, beryllium, boron, chlorine, cobalt, manganese, molybdenum, nickel, thallium, vanadium, and zinc. If eaten, drunk or inhaled, these toxicants can cause cancer and nervous system impacts such as cognitive deficits, developmental delays and behavioral problems. They can also cause heart damage, lung disease, respiratory distress, kidney disease, reproductive problems, gastrointestinal illness, birth defects, and impaired bone growth in children. A large amount of coal ash is disposed in dry landfills, frequently at the power plant where the coal was burned. Coal can also be mixed with...

Management and Managers...

Management and Managers Management is an important part of an organization. In fact the discipline of management is developed over a period of time to its present level. On the other hand managers of tomorrow are developed from the young, educated people who are knowledge workers of today. Both the management and the managers are vital component of the organization for its smooth functioning. Present day society has become a ‘knowledge society’, a ‘society of organizations’, and a ‘networked society’. Today, the major social tasks are being performed in and through structured organizations, large and small, of all kinds and sizes. And every organization is entrusted to ‘managers’ who practice the ‘management’. History of management The word ‘management’ was first popularized by Frederick Winslow Taylor to describe what he had formerly (and more accurately) called ‘work study’ or ‘task study’ which is today being called ‘industrial engineering’. But when Taylor talked about what is being called today ‘management’ and ‘managers’, he said ‘the owners’ and ‘their representatives’. The roots of the discipline of management go back to more than 200 years. But management as a function, management as a distinct work, management as a discipline and area of study, all are the products of the twentieth century. And most people became aware of management only in 1950s. Some recent studies on management give the impression that the management is an invention of late 1940s. True, before this period interest in and study of management was confined to small groups. The popular interest in management as a discipline and a field of study is fairly recent. But management, both as a practice and as a field of study, has a respectable history, in many different countries, going back almost two centuries. When the early economists,...