Effectiveness of dispersing the blow to speed up the steelmaking operation

Various methods of injecting steelmaking baths with oxidizing and neutral gases through the bottom of hearth-type furnaces have come into wider use abroad in recent years. Having decided that potential problems with the durability of the lances would preclude the injection of oxygen through the bottom of its arc steelmaking furnaces, the Moldavian Metallurgical Plant (MMZ) decided to install lances in the side of the furnace and inject oxygen deep into the bath. The gas-oxygen lances were installed in the shell of the furnace 300–500 mm below the surface of the bath. Placing the cermet lances in the shell satisfies operating requirments, makes it easier to service the lances, and allows them to be repaired or replaced in the working regime. The requirements that must be met for high-rate steel production are best satisfied with the use of refractories made by the company RHI AG. Results obtained in the course of the above-mentioned project were used to construct an algorithm that optimizes the relationship between the depth of immersion of the lance in the melt and the direction of the lance relative to the surface of the bottom of the furnace. Innovations such as these, developed by the MMZ in collaboration with the company TECHCOM Import Export to intensify steelmaking operations, are now in use on the arc furnaces at the MMZ’s ISTIL plant.     

Technical solutions to the problem of separating furnace slag from steel and subjecting the slag to its initial processing

The company TECHCOM has come up with several innovations to separate slag from liquid steel as it is tapped and flows to the ladle. The effectiveness of the methods was checked on cold models using potassium iodide and colored kerosene to simulate steel and slag, respectively. It was found that the methods proposed by TECHCOM ensure complete separation of the slag from the steel. The article also discusses the conceptual framework for a technology that allows slag to undergo its initial processing next to the steelmaking furnace.     

On the noise properties of injection-locked oscillators

This paper presents a detailed study of noise properties of injection-locked oscillators. We describe an elaborate numerical model, which offers the accuracy of the best known analytical models when analyzing a single oscillator. Those analytical models do not use perturbation theory since the Wiener nature of the noise renders small-signal analysis inadequate. Our model can be extended to any locked oscillators configuration while keeping the same accuracy. This was not done to date with any of the rigorous analytical models. We analyze unidirectionally and bidirectionally coupled oscillators operating in fundamental or harmonic-locking modes. Harmonic locking is analyzed in detail and the indirect locking process underlying it is identified while the noise of all harmonics is explored in detail. The results of the model are confirmed in a series of experiments employing electrooptic implementations with a photo-HBT-based oscillator. The various configurations we analyze and demonstrate experimentally represent important applications such as spectral purity enhancement, timing extraction, and low-jitter optical pulse generation.     

Using the DVS system for the bottom-blowing of steel in the electric steelmaking shop at the Moldavian Metallurgical Plant

Use of the injection equipment in the DVS system on electric steelmaking furnaces at the Moldavian Metallurgical Plant has shown that, other conditions being equal (consumption of oxygen and natural gas, composition of the charge materials), it is more effective than the DPP system for the bottom injection of inert gases into steelmaking baths. The system injects the energy carriers directly into the liquid metal. The results obtained from one DVS injection unit turned out to be better than those obtained from the simultaneous operation of three DPP units.     

Use of the ASIS technology at the Moldavian Metallurgical Plant

The Moldavian Metallurgical Plant has worked with the company TECHCOM to develop, introduce, and successfully use the low-waste ASIS technology for feeding aluminum shot into a stream of steel being tapped from an electric-arc furnace for preliminary deoxidation of the steel. The aluminum shot (1–4 mm fraction, with an aluminum content of 97%) functions as the deoxidizing agent and is introduced into the stream by a special injection unit. The optimum rate and angle at which the shot is introduced into the steel are determined. Both the shot-feeding operation and the task of monitoring the consumption of shot are fully automated. The technology reduces the consumption of aluminum-bearing materials by as much as 25%. The quantities of other deoxidizers and alloying elements that are used have also been optimized.     

From mediation — to innovative technologies

TECHCOM is the leader in the development and introduction of the latest equipment and systems for mixing gases, homogenizing melts in refining furnaces with respect to temperature and chemical composition, and removing nonmetallic inclusions during out-of-furnace treatment and casting.