Title

INFLUENCE OF WATER QUALITY AND OPERATING CONDITIONS ON THE WEAR OF COOLING NOZZLES IN HOT ROLLING

INFLUENCE OF WATER QUALITY AND OPERATING CONDITIONS ON THE WEAR OF COOLING NOZZLES IN HOT ROLLING

Authorship

CUNHA, RAPHAEL ALEXSANDER RIBEIRO DA; SILVA, LAYANNE RODRIGUES DA; ARAUJO, THAIS JACIANE; ARAUJO, GILMAR TRINDADE DE; SANTIAGO, GABRIEL AUGUSTO DE AVILA; ARAUJO, FABIO DE OLIVEIRA; ALMEIDA, ITALO PEREIRA GOMES DE

CUNHA, RAPHAEL ALEXSANDER RIBEIRO DA

I am this author

SILVA, LAYANNE RODRIGUES DA

I am this author

ARAUJO, THAIS JACIANE

I am this author

ARAUJO, GILMAR TRINDADE DE

I am this author

SANTIAGO, GABRIEL AUGUSTO DE AVILA

I am this author

ARAUJO, FABIO DE OLIVEIRA

I am this author

ALMEIDA, ITALO PEREIRA GOMES DE

I am this author

DOI

10.5151/2594-5297-42544

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Abstract

This work presents an analysis of the water quality used in the cooling system of the hot strip mill at Companhia Siderúrgica Nacional (CSN), correlating its physicochemical parameters with the wear observed on the spray nozzles. The Langelier Saturation Index (LSI), total suspended solids (TSS) content, water corrosivity, and operational conditions were investigated. Water samples collected during different shifts revealed a highly corrosive environment, with a strongly negative LSI (-3.04 to -3.21), low alkalinity, low hardness, and inadequate pH. Shift C showed critical TSS values (192 mg/L), with a high potential for abrasion and nozzle clogging. Additionally, the XRF analysis of residual particulates on the nozzles showed high concentrations of metal oxides (Fe₂O₃, Al₂O₃, MnO, SiO₂, ZnO) and corrosive compounds (SO₃, Cl), significantly higher than those found in the iron fines on the rolling floor, demonstrating the contribution of corrosion processes and particle transport to nozzle degradation. The proposed corrective actions aim to optimize water chemistry and the filtration system to reduce nozzle wear and ensure greater reliability in the rolling process.

THIS WORK PRESENTS AN ANALYSIS OF THE WATER QUALITY USED IN THE COOLING SYSTEM OF THE HOT STRIP MILL AT COMPANHIA SIDERúRGICA NACIONAL (CSN), CORRELATING ITS PHYSICOCHEMICAL PARAMETERS WITH THE WEAR OBSERVED ON THE SPRAY NOZZLES. THE LANGELIER SATURATION INDEX (LSI), TOTAL SUSPENDED SOLIDS (TSS) CONTENT, WATER CORROSIVITY, AND OPERATIONAL CONDITIONS WERE INVESTIGATED. WATER SAMPLES COLLECTED DURING DIFFERENT SHIFTS REVEALED A HIGHLY CORROSIVE ENVIRONMENT, WITH A STRONGLY NEGATIVE LSI (-3.04 TO -3.21), LOW ALKALINITY, LOW HARDNESS, AND INADEQUATE PH. SHIFT C SHOWED CRITICAL TSS VALUES (192 MG/L), WITH A HIGH POTENTIAL FOR ABRASION AND NOZZLE CLOGGING. ADDITIONALLY, THE XRF ANALYSIS OF RESIDUAL PARTICULATES ON THE NOZZLES SHOWED HIGH CONCENTRATIONS OF METAL OXIDES (FE₂O₃, AL₂O₃, MNO, SIO₂, ZNO) AND CORROSIVE COMPOUNDS (SO₃, CL), SIGNIFICANTLY HIGHER THAN THOSE FOUND IN THE IRON FINES ON THE ROLLING FLOOR, DEMONSTRATING THE CONTRIBUTION OF CORROSION PROCESSES AND PARTICLE TRANSPORT TO NOZZLE DEGRADATION. THE PROPOSED CORRECTIVE ACTIONS AIM TO OPTIMIZE WATER CHEMISTRY AND THE FILTRATION SYSTEM TO REDUCE NOZZLE WEAR AND ENSURE GREATER RELIABILITY IN THE ROLLING PROCESS.

Keywords

Hot Strip Mill, Water Quality, Colling Nozzles, Nozzel Wea

Hot Strip Mill, Water Quality, Colling Nozzles, Nozzel Wear