Flume Mill Scale Separation for Low-Oil Wastewater Recovery
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Solution Overview
Problem
Hot rolling mills and basic oxygen furnaces generate mill scale contaminated with oil, making it costly and environmentally hazardous, as oily mill scale cannot be recycled and often ends up in landfills, while clean mill scale is more valuable but difficult to separate effectively from wastewater.
Innovation Solution
Implementing in-process separation using grit or CDS separators in the flumes of hot rolling mills and basic oxygen furnaces to capture mill scale directly from high-speed wastewater, reducing oil contamination and allowing for efficient recycling of clean mill scale, utilizing separators like HeadCell ®< grit and sand separators from International Hydro, which separate mill scale from oil and wastewater without additional energy or environmental concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional wastewater treatment methods are used to separate mill scale, then mill scale can be recovered, but the mill scale is heavily contaminated with oil making it non-recyclable and requiring costly landfill disposal
Solution Approach 1:
The invention applies preliminary action by installing separators at the beginning of the wastewater stream in the flumes, before the mill scale has significant opportunity to contact and become contaminated with oil. This proactive approach captures clean mill scale immediately after it separates from the steel surface, preventing the contamination problem entirely rather than attempting to separate oil from contaminated mill scale later in the process
Solution Approach 2:
The invention segments the wastewater treatment process into distinct stages: initial mill scale separation in flumes using separators, followed by subsequent oil treatment. This segmentation allows the mill scale removal function to operate independently before oil contamination becomes an issue, enabling clean mill scale recovery without the complexity of simultaneous oil-mill scale separation
2Object-affected harmful factors
If additional separation equipment is added to reduce oil contamination in mill scale, then mill scale quality improves for recycling, but system complexity and cost increase
Solution Approach 1:
The invention utilizes the existing self-service characteristics of the rolling mill flume system, where wastewater naturally flows through the flumes and mill scale naturally separates from the water stream due to density differences. The separators simply capture this naturally occurring separation, leveraging the existing physical processes rather than requiring complex mechanical intervention to both separate mill scale and remove oil
Solution Approach 2:
The invention extracts only the mill scale component from the wastewater stream at the point where it naturally separates, leaving the oil-contaminated water to continue to subsequent treatment stages. This selective extraction of mill scale before significant oil contact occurs achieves high-quality recovery without requiring the system to handle the more complex problem of simultaneous oil-mill scale separation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces the oil content in mill scale, making it recyclable and reducing treatment and landfill costs, with oil concentrations in mill scale collected from flumes being significantly lower than conventional methods, and allowing for the generation of clean, valuable mill scale for internal use or sale.
Implementation Method 1
The CDS units deflect the fluid stream inflow into a separation chamber
Implementation Method 2
Heavy solids settle to the bottom of the sump in the chamber
Implementation Method 3
The screen removes the pollutants and allows the fluid to return to the stream
Data Source
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AI summary
A method for collecting mill scale from a hot rolling mill is provided. The hot rolling mill includes a flume. The method includes transporting mill scale particles in wastewater, retrieving the wastewater from a flume of the hot rolling mill and separating the mill scale particles from the wastewater using a separator. A hot rolling mill and a method for retrofitting a hot rolling mill are also provided.