Crushing and screening plant investment cost: what the budget really contains

Equipment price is not the investment budget

The first number anyone collects for a new quarry line is the machine list total, and that is exactly where budgets start going wrong. A crushing and screening plant investment cost covers the concrete the frames sit on, the medium voltage feed pulled to the site, the crane hours, the motor control centres, the chutes, the walkways, the permitting effort and every commissioning shift. Leave those out and the shortfall appears halfway through erection, usually paid for by cutting structural work or dust control. That saving comes back as an invoice inside the first operating year.

At the concept stage you cannot collect real quotations, because the general arrangement drawing does not exist yet. Process engineering solves this with the factorial estimate: take the delivered cost of the major equipment, apply an experience based multiplier, and you have an order of magnitude figure for the whole installation. It is a screening number. It tells you whether the project is worth developing; it does not authorise spending.

The installed cost factor and how it varies by plant type

A factorial estimate assumes total installed capital scales with delivered equipment cost. The multiplier depends on the phase of material the plant handles. A crushing and screening line handles solids only, and that family carries the lowest factor of all, because the piping, pumping, pressure vessel and process instrumentation load is light compared with a fluid plant.

The share column is simply the inverse of the factor. At 3.1 the machines account for roughly a third of the money and the remaining two thirds is site work and engineering. That single line reframes most budget meetings, because a first draft budget typically allocates more than half of the total to equipment and underestimates everything that happens on site.

What the factor already includes

The multiplier is not a contingency dressed up as engineering. It represents defined work packages: erection labour, transfer chutes and connecting steelwork, power distribution and cabling, measurement and control instrumentation, reinforced concrete foundations, structural steel, small buildings such as the operator cabin, and engineering plus project management services. Budget one of those separately while leaving it inside the factor and you have double counted; omit it in both places and you have a hole.

Write the battery limit down

The most common failure in factorial estimating is boundary drift, where the definition of what is included quietly changes between projects. Separate work inside the plant battery limit from outside infrastructure. Haul roads, the weighbridge, site power connection, water supply, landscaping and the administration building usually sit outside and are not covered by the multiplier. Two lines of scope definition on the first page of the estimate remove most later argument.

Crushing and screening plant investment cost: line items and the measurement each one rests on

As design matures, the factored number is replaced item by item. The table below shows which physical quantity drives each line. Measure that quantity before you request a quotation, otherwise you cannot compare the answers you receive.

The quantity column is what makes a budget auditable. Without a concrete volume the foundation line cannot be defended; without a summed installed power the transformer line is a guess. As the layout firms up these quantities harden, and the factored estimate gives way to a real budget. Layout and capacity options published for the stationary crushing plant are a practical starting point for that list.

Building the estimate step by step

Order matters, because each step consumes the output of the previous one.

1. State the annual tonnage target and the product gradation, then derive hourly throughput.
2. Draw the flowsheet and produce the major equipment list, recording installed power per item.
3. Sum the delivered cost of that equipment; this is the base the factor is applied to.
4. Apply the solids processing factor and record the order of magnitude installed cost.
5. Add outside battery limit infrastructure under a separate heading, since the factor excludes it.
6. Keep initial spares and wear stock on their own line so they never blur into operating cost.
7. Replace factored lines with quantity based estimates as design advances, tracking the drift.

Handled this way the decision rests on a set of measurable assumptions rather than one headline number. When quotations arrive you can see exactly which assumption was wrong, which is the only way the next estimate gets better.

Mistakes that break the budget

Overstating the equipment share is the first, and site work absorbs the shortfall. Treating the power supply as if the grid connection already existed is the second; the medium voltage line and transformer are a material line item in most quarry projects. Compressing erection duration and counting commissioning shifts as production is the third. Forgetting the initial wear stock is the fourth, and the plant runs until the first plate change stops it. Presenting an order of magnitude figure as an approved budget is the fifth and the most expensive.

Questions engineers ask

Does the factorial method work for a mobile plant?

Foundations, structural steel and site erection shrink dramatically on tracked or wheeled units, so the multiplier falls with them. The method is unchanged, but applying a stationary factor to a mobile project inflates the estimate. Weight shifts instead towards transport, site preparation and fuel logistics.

Why does the factor depend on plant type?

What drives the multiplier up is piping, process instrumentation and pressure equipment. Fluid plants carry a heavy load of all three. In a crushing circuit material moves through chutes and on belts, so the installation content per unit of equipment cost is much lower.

How much contingency belongs in the number?

Quoting a fixed percentage is misleading, because contingency reflects estimate maturity rather than plant size. With only a flowsheet the uncertainty is wide and the allowance is generous; as detailed design and firm quotations arrive it narrows. Manage it as a curve that decays over the project, and require a document behind every reduction.

Where to start

If the annual tonnage target and the product gradation are settled, the flowsheet and the installed power list are a day of work, and the rest of the budget follows from those two documents. Send the target gradation and the site conditions and we will return an equipment list with installed power, structured so each cost line can be checked against a measurable quantity.