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Recovering Non-Magnetic 304 Stainless Steel from Slag with FRP Gravity Separation

The Challenge

A specialized stainless steel slag processor and metal recycling operator routinely purchases slag from regional steelmakers to recover valuable metals. The plant originally operated a traditional magnetic separation line, but operational results were dismal, leading to continuous, high-value metal losses.

The core problem lay in the composition of their raw material feed: the slag was primarily sourced from 304 austenitic stainless steel production. Due to its non-magnetic austenitic crystal matrix, 304 stainless steel remains non-magnetic or weakly magnetic in its standard state.

While conventional magnetic separation is effective for magnetic grades (such as the 400 series), it fails almost completely when processing non-magnetic or weakly magnetic alloys like 304. As a result, massive quantities of 304 stainless steel particles—rich in high-cost nickel (Ni) and chromium (Cr) alloying elements—were discarded directly into tailings, severely undercutting the processor's profit margins.

The FRP Solution: Density-Based Jigging & Shaking Table Circuit

After conducting a thorough analysis of the stainless steel slag's physical properties, metal size distribution, and liberation traits, FRP designed and deployed a hybrid gravity recovery system combining mineral jigs and shaking tables.

The technical principle completely bypasses magnetic properties. Instead, it exploits the substantial specific gravity differential between stainless steel (approx. 7.9 g/cm³) and the stainless steel slag matrix (approx. 2.7–3.2 g/cm³). As long as a density difference exists, the system precisely captures both purely non-magnetic alloys and complex mixed stainless steel slag feeds.

To accommodate the wide particle size spectrum of the liberated stainless steel particles inside the slag, FRP implemented a staged classification recovery strategy:

Coarse Metal Fraction:Processed via Mineral Jig Concentrators, offering high throughput and high-capacity extraction ideal for coarse particles.

Fine Metal Fraction:Directed to Shaking Tables, utilizing high-precision hydraulic separation specifically suited for fine particle recovery.

Highlights
jig separator shaking tables

Measurable Operational Results

Since commissioning, the FRP gravity separation system has successfully resolved the challenge of non-magnetic stainless steel losses, delivering outstanding operational benchmarks:

  • Concentrate Purity >98% — Yields high-purity, furnace-ready stainless steel concentrate that is sold directly to smelters at top market value.
  • Overall Recovery Rate >99% — Staged jigging and shaking table separation provides complete size coverage, reducing metal loss to negligible levels.
  • Hundreds of Tons Recovered Monthly — Transforms previously landfilled waste tailings into immediate, recurring monthly revenue.

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Recovered Metal

High-purity stainless steel concentrate.

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Clean Tailings

Final slag tailings after processing.

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Plant Overview

Compact modular layout

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Liberation Stage

release stainless steel droplets

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Jig Separation

Separates metal by specific gravity.

Key Takeaways for Stainless Steel Slag Processors & Recyclers

In the stainless steel slag recycling industry, equipment selection depends entirely on your feed material:

  • If your feed contains strictly magnetic metals (e.g., 400 series) — Conventional magnetic separation remains viable.
  • If your feed contains non-magnetic grades like 304/316 or mixed magnetic/non-magnetic alloys — Relying solely on magnetic separation guarantees significant losses of valuable alloys.

The FRP Hybrid Gravity System can operate as a standalone stainless steel slag processing line or be integrated alongside existing magnetic circuits. Regardless of alloy grade or feed condition, FRP delivers complete, high-efficiency recovery across all particle size ranges.

Evaluate Your Stainless Steel Slag Recovery Potential

No complex laboratory assays required to get started.

Simply provide:Processing Capacity (TPH);Metal Profile (Magnetic, non-magnetic, or mixed);Raw Slag Photos

The FRP engineering team will deliver a free preliminary feasibility within 24 hours.

Contact FRP Engineering Team 👉

How can we help?

Have a question, need advice, or want to schedule an appointment? We're happy to assist with any inquiries you have about our equipment and system solutions.