Acid Regeneration for Spent Hydrochloric Pickle Liquor Sep20

Acid Regeneration for Spent Hydrochloric Pickle Liquor...

Acid Regeneration for Spent Hydrochloric Pickle Liquor  Pickling is a process which consists of chemical removal of scale (surface oxides) and other dirt from steel by immersion in aqueous acid solution. During the pickling process, acid reacts with scale as well as base steel to produce dissolved metal salts. The pickling process generates a considerable quantity of spent pickle liquor (SPL) containing the dissolved salts as well as residual free acid. This SPL is either to be disposed of after chemical neutralization with alkali or regenerated. Carbon steel is usually pickled either by sulphuric acid (H2SO4) or hydrochloric acid (HCl). But hydrochloric acid is now preferred over sulphuric acid due to the following advantages. It consistently produces a uniform light gray surface on high carbon steel. Probability of over pickling is much less. Iron concentrations can be as high as 13 %. Rinsing is facilitated because of high solubility of iron chloride. It is safer to handle when compared with sulphuric acid. Pickling is carried out at lower operating temperatures  Hydrochloric acid regeneration refers to process for the reclamation of bound and unbound HCl from metal chloride solutions such as ferrous chloride. Regenerated acid has no adverse effect on metal cleaning efficiency compared to virgin acid.  It pickles as efficiently as virgin acid. There are several processes for the regeneration of spent hydrochloric pickle liquor. A number of different process routes are available. The most widely used is based on pyrohydrolysis, hydro thermal and adiabatic absorption of hydrogen chloride in water, a process invented in the 1960s. Distillation process Distillation process has been used where there is a significant level of free acid is remaining in the SPL. Purified HCl, at the azeotropic concentration of about 15 % w/w is recovered from the ‘overs’ while the concentrated...

Ductile Iron Pipes

Ductile Iron Pipes Ductile Iron pipes are pipes made of ductile iron. They are commonly used for potable water distribution and the pumping of slurries, sewage and process chemicals. Ductile iron is a spheroidized graphite cast iron. Ductile iron pipes are a direct development of earlier cast iron pipes which it has now almost replaced. The high level of dependability on ductile iron pipes is due to its various superior properties and it is a most sought after pipe for many applications. History of ductile iron pipes American Cast Iron Pipe Company pioneered the development of ductile iron pipes and produced experimental casts of these pipes as early as in 1948. The first shipment was made in 1955. Since then production of ductile iron pipes has grown steadily and it is now a predominant piping material for conveying water and other liquids. Ductile iron As the name suggest, it is a cast iron having the property of ductility. This quality of cast iron long sought after by metallurgists, was realized in 1948. Ductile iron is acclaimed as one of the most significant developments of the century and has had an increasing impact on the industry. Besides the property of ductility, ductile iron has, in addition, strength and impact resistance much greater than that of gray iron.  Ductile iron also retains the corrosion resistance property of gray iron hence it is an ideal material for pipes. Ductile iron is produced by treating molten low sulphur base iron with magnesium under closely controlled conditions. The startling change in the metal is characterized by the free graphite in ductile iron being deposited in spheroidal or nodular form instead flake form as  gray cast iron. With the free graphite in nodular form, the continuity of the metal matrix...

Value Engineering – A Tool for Improvement...

Value Engineering – A Tool for Improvement Value engineering (VE) is a management technique that seeks the best functional balance between cost, reliability and performance of a product, project, process, system or service. It is a function oriented, systematic team approach and method to improve the ‘value’ of product, project, process, system or service by using an examination of function. Value, as defined, is the ratio of function to cost. Value can therefore be increased by either improving the function or reducing the cost. It is a primary tenet of value engineering that basic functions be preserved and not be reduced as a consequence of pursuing value improvements. Often, the value improvement is focused on cost reduction; however other important areas such as customer perceived quality and performance are also of paramount importance in the value equation. History of value engineering Value engineering was conceived at General Electric Company in early 1940s. At that time due to the World War II, there were shortages of skilled labour, raw materials, and component parts. To overcome theses shortages, Lawrence Miles, Jerry Leftow, and Harry Erlicher at G.E. looked for acceptable substitutes. They noticed that these substitutions often reduced costs, improved the product, or both. What started out as an accident of necessity was turned into a systematic process. This technique was named as ‘Value Analysis’.  Besides value analysis, value engineering is also sometimes known as value management and value methodology. The job plan A value engineering study generally encompasses three stages. Stage 1 consists of preparation. During stage 2, multi phase job plan is carried out. Stage 3 consists of documentation, implementation and audits. Value engineering is usually done by systematically following a multi stage job plan which is known as ‘value analysis job plan’.  The job plan is carried...

Water Management and Pollution Control in Steel Plant Sep04

Water Management and Pollution Control in Steel Plant...

Water Management and Pollution Control in Steel Plant An integrated steel plant incorporates a number of processes right from raw material preparation to rolling of finish steel. All these processes need water. When the water is used in these processes it gets contaminated with pollutants in various amounts and concentrations. Typical requirement of water in various processes in steel plant needs 100 to 200 Cum per ton of steel. Pumping capacities for this amount of water is needed in the steel plant. The requirement of makeup water depends on the water treatment and recirculation facilities in the plant and usually is in the range of 2 to 4 Cum per ton of steel. Water management in an integrated steel plant is very important for its successful operation since the integrated steel plant needs a large amount of water for its operation. During the operation of the plant this water gets polluted. It is very difficult to separate water pollution control from water management in the plant. A good water management leads to a decrease in pollution control of water while at the same time pollution control of water needs good water management.  Good water management requires zero or minimum water discharge from the plant. This is achieved by incorporating elaborate water treatment systems for recirculation of water. This reduces water consumption since there is a reduction in the requirement of makeup water. It also reduces the water pollution since the water discharge from the plant boundary becomes nil or negligible.  Further it reduces the necessity and cost of treatment of polluted water before its discharge from the plant boundary. Use of water Water has many varied uses in the iron and steel plant and the quality of water needed for each use also vary....