There are two basic ways of making steel. Steel producing sites which use blast furnaces, which make iron which is refined into steel, are termed 'integrated sites'. They most commonly use Basic Oxygen Furnaces (BOF) to turn the iron into steel. The liquid iron from the blast furnaces is taken to the BOF shop where pure oxygen is blown into the iron at supersonic speed through a lance positioned in the mouth of the BOF and this removes the carbon and other impurities. Burnt lime and certain other 'fluxes' are added to the BOF to make a liquid slag which will absorb the impurities and so keep them separate from the steel. There are many variations in the detail of the BOF but they are all broadly the same. Alternative names refer to the same thing, the most common being 'oxygen steelmaking', 'oxygen converter' (it converts iron into steel), 'LD converter' – where the LD today refers to the two Austrian plants where the process was developed, Linz & Donawitz. 'Basic Oxygen Steelmaking (BOS)' and even 'vessel' are other terms commonly employed, the ‘basic’ referring to the type of lining in the vessel which has to be alkaline (basic) in nature when treating iron made from ores containing phosphorus. The important thing is that integrated sites make liquid iron from ore and turn it into steel.
A point which commonly confuses is that all the heating energy in the BOF comes from the oxygen burning off the impurities, mainly carbon. There is no other source of heating in the vessel. The carbon is burned off producing carbon monoxide, which can be collected and used as a fuel to re-heat steel in the rolling mills.
The electric arc furnace
operates as a batch melting process producing batches of molten steel known "heats". The electric arc furnace operating cycle is called the tap-to-tap cycle and is made up of the following operations:
Furnace charging
Melting
Refining
De-slagging
Tapping
Furnace turn-around
Modern operations aim for a tap-to-tap time of less than 60 minutes. Some twin shell furnace operations are achieving tap-to-tap times of 35 to 40 minutes.
Concast stands for continuous casting of bloom / billet and slab.
It is essentially continuous conversion of liquid / molten steel to solidified form without affecting mechanical properties as achieved by conventional, lengthy and uneconomical route of ingot mould stripping and soaking pits. Thanks to the revolutionary process, the steel making and rolling processes have been made quasi – continuous. The instrumentation and control system plays a vital role in holding liquid/solid phase of steel with reference to time, well within control, avoiding breakout / jamming of steel. To avoid under / over cooling, what really matters is accurate water flow measurement using highly accurate Magnetic flow meters, linked with strategic control valves of water . Pressure which is an equally important parameter can be accurately sensed by using Pressure Transmitters. Primary (Mould) water cooling is based on accurate control of differential temperature (4-6° C) between inlet and outlet for which the water flow rate is manipulated. The system provides excellent flexibility to metallurgists in establishing cooling cycles and venturing into continuous casting of increasingly difficult grades of special and alloy steel, without problems in quality.
A Repair Technology of Copper Parts —— CNK+ Technology
Technical principle and development of CNK+ technology
Compared with conventional surface processing technologies, this technology uses high energy beam such as electron beam, laser beam and ion beam to process the surface of materials(coating, surface hardening,etc.) and gain better effect. Therefore, it is one of advanced manufacturing technology. CNK+ can coat evenly various or multilayer of alloy materials (nanocomposites) withmaximum thickness 150 mm!This revolutionarytechnology reaches surface remaking of base material.CNK+ technology have been applied to copper-based parts repairing for dozens of steel plants in several year.. Take crystallizer of continuous casting machine for example, the accumulative yield is over 10 million tons by CNK+ repairing.
According toproperties offered by clients like abrasion resistance, self-lubricating, high temperature resistance, high hardness, high strength, anti-extrusion and other physical properties, CNK+ compounds the special metal alloys or bi-metal materials with base materials. Also, the thickness of the composites and regenerate materials can be adjusted as required. There is much breakthrough in plating metallic composite of ceramic treating on kinds of base materialsand surface modification made by CNK+. So far, it has been applied to many other fields of aerospace, petrochemical industry and marine power,etc.
Economic benefit & cooperation
1. Compared with traditional chromium alloy plating technology for tubular crystallizer, CNK+ technology improve repair capacity and material performance. This technology has reached or exceeded the technical level of similar technologies in the world. It increases service life of products 3 times.
2. Remanufacturing capability of CNK+ technology makes copper-based parts of crystallizer to realize multiple recycled avoiding melting down. For scrapping crystallizer, almost all the parts due to mechanical damages or excessive abrasions can be recycled.
3. CNK+ copper parts repair technology has been applied to various of copper-based parts and crystallizers whose copper tube diameter is less than 1000 mm, maximal size of copper plate reach 2500mm and weight is less than 10 tons. So far, the technology has been used for repairing copper-based parts and crystallizers for several steel plants accumulative yield of tube blank is over 10 million tons.The cost is just half of buying a new one.
4. CNK surface coating technology of high energy beam has been accepted and applied widely. Applying CNK+ technology to repairing crystallizer can promote the upgrading of technology, greatly reduce the cost of production and improve competition ability for steel enterprises. Compared with other surface modification technology, CNK+ has the least influences on properties of the base material and can compound the nanocomposite with base material tightly without peeling off.