Steel Slag Slurp: Turn RimWorld Trash into Treasure

Quick Start Guide: Smelting Your First Slag Chunk

Crash site with drop pods and steel chunks in RimWorld

Crash site with drop pods and steel chunks - this is where your steel treasure hunt begins!

If you just want to turn those slag chunks into steel right now, follow these steps:

Research & Build an Electric Smelter: Ensure you have Electric Smelting researched (in Crashlanded scenario, this is available from start). Construct the smelter (requires 170 steel + 2 components). It's under Production in the Architect menu. Place it indoors and connect power (it draws 700W continuously).
Set a Dumping Stockpile for Slag: Designate a Dumping Stockpile Zone near the smelter. By default these allow steel slag chunks. Haulers will bring any slag on the map to this pile. (Tip: you can click any slag chunk, then press "Haul" if available, or use the method in step 4 to mark multiple.)
Add the Smelting Bill: Click the Electric Smelter → Bills → Add Bill → "Smelt metal from slag". This recipe is what turns chunks into steel. Configure the bill radius to include your slag stockpile (e.g. 20 tiles if nearby) so colonists only grab local chunks. You can set it to Do forever or a certain count.
Haul Chunks in Range: Make sure your chunks are in the smelter's allowed radius. To quickly haul scattered chunks, double-click one slag chunk to select others nearby, then press "P" (the default haul command hotkey) – they'll be marked for hauling to the dumping zone. If you have the Allow Tool mod, you can use "Haul Urgently" to prioritize this.
Assign a Worker: Any colonist with Crafting enabled can do smelting. Ensure at least one pawn has Smithing/Smelting at a high priority. They will bring a chunk to the smelter and begin smelting. Each chunk takes 400 ticks (6.67 sec) of work, after which 15 steel appears in the smelter's output. Voila – free steel!
Power Off When Not in Use: The smelter uses a lot of electricity. Toggle it off when idle to save power (it won't auto-shut like some buildings). Just remember to turn it back on when you get more slag. For handling power outages and electrical emergencies, see our solar flare survival guide.

Quick math: Smelting 4 slag chunks gives 60 steel, which is enough to build vital things like a stove or some turrets. The work time (~26.7 seconds of pawn labor for 4 chunks) is often quicker than mining an equivalent amount (which could take ~32 seconds plus travel for 60 steel at Mining skill 8). In short, smelting pays off early-game.

Early-Game Steel: Slag vs. Mining vs. Scrapping

One of the first hurdles in RimWorld is running out of steel. You start with some, maybe mine compacted steel veins, but suddenly you're out – and vital projects (like electricity or defenses) are on hold. This is where steel slag chunks come in as a clutch resource that many beginners overlook.

Why Smelt Slag Chunks? (Efficiency Breakdown)

Steel slag chunks are those gray hunks left behind from destroyed structures, crashed drop pods, and some quest incidents. On their own, they're useless – they even make your base ugly (Beauty = –8). However, each chunk yields 15 steel when smelted at a cost of 6.67 seconds of work. That's ~0.45 seconds per steel, which is actually more efficient than mining steel in many cases! For tips on managing the ugliness they cause, check our environment beauty guide.

Steel Production Efficiency: Work seconds per 1 steel (lower is better)

Smelting Slag

0.45s

Mining (Skill 8)

0.79s

Mining (Skill 16)

0.50s

Deep Drilling

7.30s

Mech Shredding

0.33s

The chart above shows that at low-to-mid skill levels, smelting slag chunks beats mining for pure efficiency. Of course, mining yields more total steel per node (each vein tile gives 35–40 steel), but slag is essentially free steel lying around waiting to be used.

When to Prioritize Mining Instead

If you have a high-skill miner (16+), their efficiency approaches or exceeds slag smelting
If slag chunks are far away and hauling is a bottleneck
If you've exhausted slag on the map
If you desperately need steel right now and there's a big vein right next to your base

Pro Tip: Assign a novice colonist to smelt slag while your better miner focuses on components or other tasks. This tags in an otherwise idle pawn to contribute to steel income.

Other Early Steel Sources in Brief

Crashed Ship Chunks: Can be deconstructed for 20 steel + 2 components each
Weapons & Armor Smelting: Yields about 25% of the item's material in steel
Trading: Buy steel from traders (often cheap)
Quests and Events: Quest rewards or cargo pod drops

Managing Slag: Hauling, Storage, and Avoiding Chunks Everywhere

A RimWorld stockpile zone containing steel chunks and other resources - proper storage is key to efficient slag management!

Hauling 101: Why won't they haul my slag?

New players often run into this: steel slag chunks (and stone chunks) seem to just sit there, even with idle haulers. Usually, the reason is storage settings. Here's the checklist:

Use a Dumping Stockpile: By default, regular stockpiles do NOT include chunks. Conversely, Dumping Stockpiles by default include stone and steel slag chunks.
Check Storage Capacity: If your dumping stockpile is full or too small to accept more chunks, pawns will stop hauling.
Accessible Area: If chunks are outside your allowed area, pawns won't haul those.
Forbidden Items: If an item is marked forbidden (red X), they won't touch it.
No Hauling Bots/Colonists?: Make sure someone can haul.

Speeding Up Chunk Hauling

Double-Click Selection: Double-click one slag chunk to select all visible on screen, then press "P" to mark them for hauling.
Haul Urgently (Allow Tool mod): Marks them to be hauled with top priority.
Caravan Trick: Form a one-person caravan, load all chunks, then immediately cancel the caravan so they unload at home.
Pack Animals: Use animals like muffalos or horses for hauling.
Multiple Dump Sites: Create temporary dumping zones near slag clusters.

Dealing with Slag Build-up (Storage Solutions)

A RimWorld stockpile zone configured to store only chunks - specialized storage keeps your base organized!

Expand or Relocate Dumping Zones: Move excess slag away from your living areas.
Deep Storage Mod: Adds special storage furniture like steel slag chunk dumpsters that can hold 1200 chunks in a 3x4 tile space.
Atomize via Smelter: Best way to reduce slag clutter is to smelt it down.

Warning: Having hundreds of physics objects like slag chunks can impact game performance. Consolidate them via smelting or storage when possible.

Slag Chunks as Defensive Tools

Those slag (and rock) chunks can be used for defense. Raiders and colonists can use chunks as cover (50% cover effectiveness).

Cover Value 50%: Slightly worse than sandbags (57%) but free and available early
Movement Speed: Chunks slow movement as pawns "climb" over them
Blocking Building Spots: Can't build where chunks lie, delaying sappers

Tactical Tip: Create "chunk stockpiles" in killzones to encourage raiders to stop at suboptimal cover which you have ranged weapons trained on.

Mid-Game: Scaling Up Steel Production

A top-down view of a RimWorld base layout, highlighting room functions and logistics - efficient base design supports better resource management!

Deep Drilling vs. Smelting: a Balanced Approach

Around mid-game, you likely research Deep Drilling and the Ground-Penetrating Scanner. This unlocks infinite steel in theory, but deep drilling is slow per unit and requires a lot of upfront work.

Method	Yield	Work Time	Requirements	Best For
Smelting Slag	15 steel/chunk	0.45s/steel	Electric Smelter, Power	Quick steel, efficient labor
Mining (Skill 8)	35-40 steel/node	0.79s/steel	Mining skill, accessible veins	Early game, accessible steel
Deep Drilling	1000-3000/deposit	7.30s/steel	Research, Scanner, Power	Bulk steel needs, late game
Trading	Varies	N/A	Silver, trader availability	Emergency needs, convenience
Mech Shredding	10-20/mech	0.33s/steel	Machining table, dead mechs	Post-raid resource recovery

Strategy Tip: Assign different pawns to different steel sources - skilled miners to deep drilling, lower-skill pawns to smelting.

Steel Slag from Raids: The More You Fight, The More You Smelt

As difficulty ramps up, raids (especially drop pod raids) bring you slag. In RimWorld 1.5, certain large mechanoids now drop Mechanoid Slag Chunks when killed.

Each big mech = +15 steel from its slag
Each drop pod = +15 steel
Ten drop pods crashing = 150 steel lying on the ground (once processed)

Component Crunch: Mods to the Rescue (Refining Slag)

By mid-game, components often become the limiting resource. Modders have created solutions involving slag:

Steel Slags Refined: Lets you refine slag chunks into components (1 slag yields 1 component)
Slag Refined Plus: Doubles steel output to 30 per chunk and occasionally yields components
Fueled Smelter: Adds a fueled variant of the electric smelter for tribal starts

Late Game: Slag in the Endgame and Beyond

An elaborate and well-defended RimWorld base with symmetrical design - even advanced colonies benefit from efficient slag recycling!

In late game, you might think steel slag is irrelevant – you have deep drills on every resource, maybe an output of thousands of steel, and components fabrication in full swing. However, slag still has its uses even in endgame scenarios:

Orbital Trade Commodity

Excess steel can be turned into steel sculptures or other goods for trade, or you can just trade steel directly. Think of slag as an investment that can be liquidated.

Repair and Maintenance

Massive bases with many drills, turrets, and construction projects will consume steel continuously. Slag chunks from constant raid events essentially feed back into maintaining defenses.

Late Game Ritual: After each raid or battle, dedicate time to recycle everything – slag to steel, mech corpses to resources, fallen weapons to smelt. This circular economy keeps your colony sustainable.

Wealth Control for Endgame Raids

If you are preparing for the endgame (like the ship launch sequence), you might hold off smelting some slag to not spike wealth until you're ready. Then right before starting the reactor, smelt a ton to have extra steel for emergency turrets or walls during the 15-day onslaught.

Mechanoid Recycling Program

With the Biotech DLC, if you have mechanoid gestators and bandwidth, you might deliberately farm certain mechanoid types to shred and smelt. It's like a bizarre recycling plant: use enemy material against them.

FAQs and Troubleshooting

I built an Electric Smelter but there's no option to smelt slag, only weapons. Is this a bug? +

Make sure you researched Electric Smelting (if your scenario didn't start with it). Without the research, the smelter will only show weapon/apparel bills and not the slag recipe. If it's researched and still not showing, check that you built the right bench – Electric Smelter is different from the Electric Smithy. The smithy doesn't do slag.

Do I need to refuel the Electric Smelter? +

No, it's electric (despite the confusing fact RimWorld has a Fueled Smithy but not a Fueled Smelter in vanilla). Once built and powered, it's always on (draws 700W) until you flick it off. It doesn't consume chemfuel or wood.

Why are my pawns taking forever to haul one chunk at a time? It's so inefficient! +

Unfortunately, in vanilla a pawn can only carry one chunk per haul trip due to weight (15 steel weighs 7.5kg vs. an 8kg chunk – they can't carry multiple 8kg chunks because default carry capacity is 35kg for humans, but volume-wise they just don't stack chunks). This is why hauling chunks is laborious. Using pack animals or the caravan hack can move many at once, as discussed. There's also a mod called Pick Up and Haul that allows pawns to grab multiple items in their inventory.

Is smelting slag really worth the time? 15 steel feels low for how much work it seems to take. +

It's better than it sounds. Remember, smelting slag takes only 6.67 seconds of work. Comparatively, crafting a simple weapon or stone blocks takes much longer per unit. Slag chunks are effectively 15 steel delivered to your base (once hauled) – if those same 15 steel were still in a vein, you'd have to go get them and possibly dig through rock. Slag is literally lying on the ground ready to use.

What about Granite or other stone chunks? Can I smelt those? +

No – stone chunks are turned into stone blocks at a stonecutter's table, not smelted. Only steel slag chunks and the special mechanoid slag chunks are smeltable for steel.

Each slag gives 15 steel – is that affected by anything? Like storyteller, difficulty, pawn skill? +

The 15 steel is fixed per chunk in vanilla, not affected by difficulty. Pawn Crafting skill doesn't affect yield (only speed via General Labor Speed). The only time it was different was historically: in earlier alphas it was 10 steel per slag, then 20 in B19, and now 15 since 1.1.

Can I get steel slag chunks in biomes with no ruins or crashes, like Sea Ice? +

Initially, possibly not many – unless your scenario dropped some. However, you will get slag from any drop pod that comes (e.g. cargo pod events, drop pod raids). On Sea Ice specifically, cargo pods happen and leave slag, and any spacer crash pods leave slag debris too. So even on an ice sheet with no rock or ore, eventually slag can appear via events.

What structures produce slag when destroyed? +

According to the Wiki, steel buildings (excluding walls and doors) drop slag when destroyed. This includes things like turrets, generators, etc. Also, raider drop pods and cargo pods produce slag on impact. Orbital trader pods and quest pods do not leave slag (they vanish magically). If you blow up an ancient ruin or a crashed ship part (poison/psychic ship), you might get slag. Generally, if something metal goes boom, check for slag after.

Conclusion: Turning Trash into Treasure

In the harsh world of RimWorld, resource management often makes the difference between a thriving colony and a doomed one. Steel slag chunks embody this – what looks like map trash is actually a treasure trove waiting for a clever player. We've seen how, through a bit of work, slag chunks can shore up your steel supplies, enabling you to build that extra turret, that vital component, or simply keep the lights on. We've also seen that even junk can serve a purpose in defense and strategy (smelt it or shoot from behind it!).

Think of slag as the RimWorld equivalent of scrap recycling in real life: it's not glamorous, but it's efficient and sustainable. You're literally pulling your colony up by its bootstraps, melting yesterday's wreckage into tomorrow's hope. There's a certain satisfaction in that cycle. Your colony's story might include a chapter where the colonists, low on resources, frantically hauled battlefield debris to the smelter to rebuild – a tale of ingenuity and grit.

So next time a raid leaves your base in shambles, don't just rebuild – recycle. Turn those scars into supplies. In RimWorld, adaptability is king, and using steel slag chunks is a prime example of adapting to what the game throws at you.

Good luck, and may your smelters never go cold!

Action Items

Now that you're armed with knowledge, here are some actionable steps to apply it:

Designate a slag dumping zone near your base right now.
Build an Electric Smelter ASAP (if you haven't) and add the slag smelting bill.
Scan your map for slag chunks (double-click one to find others) and haul them in.
Check mod options if you need a boost (Deep Storage or Slag Refined mods).
Next raid you face, have a plan for the aftermath – and look forward to the extra steel it'll provide!

With these steps, you'll turn RimWorld's scrap into your strategic advantage. Happy smelting, and have fun on the Rim!

Patch History

Date	Change Note	Impact on Early-Game
Alpha 17 (2017)	Introduced steel slag smelting – Electric smelter recipe added. Yield 10 steel per chunk.	Gave players a new steel source early on, but low yield (10) made it a marginal gain.
Beta 19 (Sept 2018)	Yield increased to 20 steel per slag chunk.	Huge buff – suddenly slag became very lucrative, encouraging early smelter rush for 2x steel vs before.
Version 1.1 (Apr 2020)	Yield reduced to 15 steel; mech disassembly yield nerfed.	Brought slag output to a balanced middle ground. Early-game now gets 15 per chunk, making smelter still worthwhile but not overpowered.
Version 1.3.3200 (Dec 2021)	Mass of slag increased 5 → 8 kg.	No change to steel output, but stopped the "carry more steel as slag" trick. Early caravans can't abuse slag weight now. Minor early-game effect, mostly caravan logistics.
Version 1.5 (Apr 2024)	Mechanoid Slag Chunks introduced. Large mech kills drop slag.	Mid/late-game steel injection – not directly early-game, but means even first mech cluster or boss provides extra 15 steel. Indirect early benefit if mechs appear.