In kiln and furnace work, material selection is often misled by names. The real dividing lines are only three: delivery form, energy needed for forming, and how the final structure is densified. Get these three right and you will almost never choose wrong.

[Image: three material appearances side by side - paste/particles/powder or slurry]

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1) Plastic refractory: shaped by "hand," bonded by "stickiness"

Plastic refractory is delivered in a plastic state, like a kneadable mass. It does not chase extreme density; it focuses on conformability and controllable local repair: it can be stuffed into gaps, pressed into corners, and troweled onto irregular surfaces.

You will use it in these scenarios

• Furnace doors, around burners, arch feet, corners, holes, local repairs
• Tight spaces where large equipment cannot be used and where you need to "shape while you build"

Its value

• Strong shape adaptability, high construction tolerance
• Friendly to complex geometry, can fill gaps in place

Its trade-offs

• Hard to reach extremely high density
• Low efficiency for large areas; not suitable as the main lining solution

[Image: close-up of hand patching around furnace door/burner]

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2) Ramming mix: shaped by "compaction," resists corrosion by "density"

Ramming mix is delivered as loose granules or powder with very low moisture. The core is not "smear it on" but "press it in": lay material in layers, then use a pneumatic hammer/rammer to squeeze out voids and form a high-density structure. Higher density means better resistance to penetration, scouring, and corrosion.

You will use it in these scenarios

• Induction furnace working lining/bottom
• Tapholes, slag channels, launders, electric furnace bottoms, and other heavy scouring zones

Its value

• High density, strong penetration resistance
• Better for combined conditions of "molten metal/slag repeated scouring + chemical attack"

Its trade-offs

• High labor intensity, slower speed
• Sensitive to construction consistency: if layer thickness, ramming energy, edge compaction, or dry-out curve drifts, life drifts

In practice, ramming mix life differences often come not from "a slightly different formula" but from "a big construction gap." Xinhui typically writes grading, layer thickness, ramming rhythm, and dry-out milestones into construction points and provides parameter boundaries by furnace type. The goal is to stabilize density and the sintered shell formation process and avoid large life swings between crews for the same furnace type.

[Image: layered ramming with a pneumatic hammer / induction furnace lining installation]

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3) Gunning mix: shaped by "spray," wins schedule with "speed"

Gunning mix is designed for spraying: powder or slurry is projected onto the substrate by air/pressure to quickly form a refractory layer. The advantage is direct: fast. It fits large-area repairs, tight shutdown windows, and schedule-driven projects.

You will use it in these scenarios

• Rotary kilns, boiler furnace walls, large-area lining repairs
• Conditions where you need to restore thickness quickly and form a protective layer fast

Its value

• High construction efficiency, large coverage
• Controllable thickness, good for "build thickness, resurface, emergency repair"

Its trade-offs

• Sensitive to base preparation, spraying parameters, and rebound control
• Different spraying modes (dry/wet/semi-dry) have different strength development and dry-out requirements; if done poorly, hollows and loose layers appear

[Image: large-area gunning with spray gun]

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4) Use a single "decision table" to choose directly

What you need most	Preferred material	Reason
Irregular shapes, corners, holes, local reinforcement	Plastic refractory	Strong conformity, controllable by hand
Resist scouring, slag attack, penetration	Ramming mix	Compaction-formed, high density ceiling
Large area, short schedule, small shutdown window	Gunning mix	Highest spraying efficiency

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5) One-sentence summary (on site)

• Plastic refractory: for "shaping."
• Ramming mix: for "density."
• Gunning mix: for "time."

[Image: diagram matching three materials to typical locations]