AutoGoldElectrolysis: Gravity-Fed Gold Recovery Concept

Intro

AutoGoldElectrolysis was a design concept for automating part of the gold recovery process from Ti/Au-coated glass slides or chips. The idea came from a practical lab problem: gold-coated chips are expensive, first-use performance is strongest, reuse is limited, and failed fabrication runs still contain recoverable material.

The current direction is a largely vertical, gravity-fed system using chemically compatible trays, tubing, filtration, valves, and electrode positioning. The design assumes the final chemistry would require formal lab review before any physical build.

Purpose

The project asks whether a small benchtop system could recover valuable material from used or failed gold-coated lab substrates instead of treating them purely as waste. It is also an exercise in chemical compatibility, fluid handling, and automation boundaries.

The concept matters because the manual recovery process involves corrosive chemistry and close attention. A clear, contained, step-by-step device could make the process easier to review, but only if the chemistry, materials, waste path, and safety controls are approved first.

Design concept

The material list is the center of the design. Planned materials and components:

HDPE flat-bottom trays
Polypropylene instrument trays and bulkhead fittings
EPDM gaskets
PVDF inline filter
High-purity polypropylene tubing
Polypropylene ball valve
Graphite and stainless steel electrode materials
Custom slide holder, with ABS or PP only considered outside the high-risk wetted path
Rigid U-shaped valve actuation concept

The system is intended to be vertical and gravity-fed rather than pump-driven. The user would add the necessary solutions into a contained reservoir, then let simple logic move the process through its steps. That choice keeps the risky chemical path passive where possible.

Design decisions

Decision	Selected direction	Why it fits the concept	Tradeoff / next step
Fluid movement	Gravity-fed vertical layout	Avoids adding a pump to a corrosive chemical workflow	Flow control depends more on valves and geometry
Tray materials	HDPE and polypropylene	HDPE fits simple containment; PP fits standard lab-fluid trays and fittings	Must be reviewed against the final approved chemistry
Fittings and tubing	Polypropylene fittings and high-purity PP tubing	Keeps the wetted path materially consistent and avoids improvised printed plumbing	Adapter stack needs simplification before build
Filtration	PVDF inline filter	Gives a defined way to trap particulates in the flow path	Adds pressure-drop and replacement questions
Avoided direction	PETG / ordinary printed wetted parts	Too hard to trust around strong acids, stress cracking, and long exposure	Printed parts can still help as dry holders or actuator pieces
Build status	Design-only until safety review	Correct boundary for a corrosive lab process	Requires approval before prototyping

Current status

Design-only concept. Not built, tested, funded, or lab-approved. The value here is material-selection reasoning, containment planning, and a clear safety boundary.

Future work

Confirm chemical workflow with lab approval
Complete CAD
Review chemical safety and containment
Verify material compatibility
Prototype only after permission, funding, and safety review

Why recover gold at all

AutoGold came from a real fabrication frustration, not from wanting a dramatic chemistry machine. The lab uses Ti/Au-coated glass slides and chips. The first use is usually the strongest, reuse is limited, and failed or over-evaporated fabrication runs can still leave expensive gold sitting on unusable substrates.

The design question was whether that waste could be handled more deliberately. If the lab already has a corrosive recovery workflow, could the physical process be made more contained, more reviewable, and less dependent on improvised handling?

That is the useful boundary of the project. It is a design concept for a contained workflow. It is not built, tested, funded, approved, or safe to treat as a procedure.

Materials are the mechanism

In a corrosive recovery concept, the material list is not a shopping appendix. It is the mechanism. The wetted path decides whether the design is even reviewable.

The current list points to HDPE flat-bottom trays, polypropylene instrument trays, PP tubing, a PP valve, glass-reinforced PP bulkhead fittings, EPDM gaskets, a PVDF inline filter, graphite and stainless electrode materials, snap clamps, quick-connect lines, adapters, and a slide holder. That mix says the design was trying to keep containment and fluid handling in common lab-compatible plastics instead of casual printed parts.

HDPE makes sense for containment trays because it is cheap, tough, widely available, and broadly resistant to many lab chemicals. Polypropylene makes sense for tubing, valves, fittings, and secondary trays because standard fluid-handling parts already exist in PP. PETG or ordinary printed wetted parts would be harder to trust around strong acids, oxidizers, heat, stress cracking, and long exposure. Printed parts can still belong in dry holders or actuation pieces; they just should not quietly become the chemical boundary.

Gravity reduces what can fail

The vertical layout is not just a shape preference. It avoids adding a pump to a chemical path that already has enough risk. Pumps add seals, tubing stress, priming behavior, backpressure, cleaning problems, and more wetted moving parts.

Gravity, valves, trays, and a rigid actuator create a more inspectable sequence: contain solution, expose the slide, drain through a defined path, filter particulates, and isolate waste or recovered material. It is not fancy logic. That is the point.

The fewer active wetted parts, the easier the failure analysis becomes. If something leaks, sticks, clogs, or reacts badly, the review can focus on a small number of physical interfaces instead of a pump-driven system with hidden internal volumes.

Why aqua regia enters the reasoning

Gold is chemically stubborn, which is why ordinary acid thinking is not enough. Aqua regia enters the design conversation because it is a known way to dissolve noble metals such as gold in lab and microfabrication contexts. That does not make it casually usable. It makes the safety and compatibility problem more serious.

The important design inference is not "use this chemistry." It is: if the recovery path involves aqua-regia-like or other aggressive acid/oxidizer chemistry, the device must be designed around containment, compatibility, venting/safety review, waste handling, and approval before anything is built.

If the final approved chemistry changed, the structure of the design would still be useful. Any serious gold-recovery chemistry would still force the same questions: what touches the liquid, what can crack, what seals, what clogs, what happens when the reaction heats or fumes, and where the waste goes. The exact compatibility table would change; the design discipline would not.

The gasket and filter are not minor parts

The EPDM gasket and PVDF filter are small line items, but they carry real design risk. A gasket is not just something that prevents dripping. It decides whether the system maintains a controlled boundary between solution and everything else.

EPDM may make sense as a sealing candidate in some chemical systems, but it would need final compatibility review against the exact chemistry, concentration, temperature, and exposure time. The design should not pretend that a gasket material is safe just because it appears in a parts list.

The PVDF inline filter makes a different kind of claim: particulates or recovered material should have a defined capture path instead of being left to settle wherever the geometry allows. That adds questions about clogging, replacement, pressure drop, and disposal, but those are better questions than having no filtration boundary at all.

Boundary of the concept

AutoGold was not built, tested, funded, or approved. That boundary is not a weakness to hide; it is the correct way to present a corrosive lab concept.

The useful work is the architecture: define the flow path, choose materials around chemical compatibility, separate containment from filtration, avoid unnecessary wetted motion, and keep the design simple enough that a lab could review it honestly.

Any stronger claim would misrepresent the project. The design is at the stage where the right next step is not fabrication. It is chemistry confirmation, safety review, compatibility review, and permission.