In 1974 Corporación Aceros de Guatemala founded the company Hornos, S.A. at the Aceros plant in zone 12. Operations began with the installation of two electric arc furnaces and an ingot system, which intermediate product consists in the production of steel ingots, using scrap metal as its raw material. Monthly production capacity, at this time, was one thousand tons. The first casting was 6 tons, but in August 1994 the steel plant was moved to Parque Industrial Sidegua for the production of 150 mm X 150 mm, 130 mm x 130 mm and 100 mm X 100 mm section billets, with an installed annual capacity of 500,000 tons.
Scrap metal is the raw material used to procure steel in the electric arc furnace. Given that we, at Aceros de Guatemala, pay special attention to the quality of the scrap metal, it is submitted to strict controls and inspection both at its place of origin and when it is received at the plant.
Scrap Metal Classification
Aceros de Guatemala has a scrap yard where the classification process is carried out in strict control according to its density and chemical analysis. We also have a plant where number 2 class scrap metal is crushed and processed to turn it into a higher density product; in other words, into number 2 class scrap metal. The plant also includes a magnetic separator to separate ferrous from non-ferrous materials.
The company has two furnaces: one Electrical Arc Furnace (EAF) and one Ladle Furnace (LF). It also has a continuous casting machine for steel billet production.
The Electric Arc Furnace (EAF)
The state-of-the-art German-manufactured Fuchs Electric Arc Furnace has a 70 steel ton capacity. It uses electrical energy to cast the scrap iron circulating through three 20 inch diameter graphite electrodes and an Italian MORE chemical injection system. It is made up of three burners operating with diesel-oxygen, two supersonic speed oxygen injectors and two carbon injectors which, through chemical reactions, provide energy to the steel bath and also form the molten metal foam (a non-metal solution or mixture made of oxides, primarily, Cao, Si02 and Feo) so as to take advantage of the electrical energy generated through the electric arc. This system is regulated by a software program that systematically performs all the operations. Scrap smelting, as well as oxidation operations are carried out in this furnace; chemical analysis are performed and it is subsequently emptied into a pot at a temperature of approximately 1,600°C.
Ladle Furnace (LF)
Steel refining is carried out in the Ladle Furnace. It consists of a pot (known as the “ladle”), covered with refractory material and preheated to 1,000°C; three 12 inch diameter graphite electrodes and a porous cap at the bottom of the pot through which argon gas is injected to homogenize the temperature of the steel and allow impurities to float and become trapped in the slag. Chemical reactions occur in this furnace by adding deoxidizing materials and steel-making lime to lower the concentration of both sulfur and oxygen present in the steel. Materials such as carbon, manganese, silicon and vanadium ferroalloys are also added to adjust the chemical composition of steel. After the desired chemical analysis is perfectly adjusted, by sending samples to the quality and 1,600°C temperature control lab, the steel is transferred to the continuous casting machine.
The liquid Steel proceeding from the Ladle Furnace is received here, where a form changing process –from liquid to solid form—is carried out through cooling with previously treated water throughout the entire course run by the billets until they reach the straightening process. The Continuous casting machine is made of a revolving turret, a distributor, refrigerated copper casts, pulling machines, straightening machines and oxy-fuel torches that cut the billets to the requested measure. The billets are sent to the stock yard and the steel furnace, where the hot billets are loaded.
Billet Quality Control at Sidegua
SIDEGUA performs strict quality control with the use of two high-precision optical emission spectrometers, THERMO SCIENTIFIC ARL 3460 OES, where the steel chemical analysis is performed throughout the entire process. Currently 14 elements are analyzed but full analysis capacity includes 22 elements. The analysis is sent to the computer monitors located in the furnace booths so that the operator may modify the analysis in accordance with the grade of steel being manufactured. All billets are marked with the casting number to identify any deflection.