Dump Leaching vs. Heap Leaching for Copper: A Guide to Maximum Recovery

What is Dump Leaching?

Dump leaching is simple. It is used for low-grade ore. The copper content is very low. Usually less than 0.5%. We take the waste rock. We pile it up. We do not crush it. This is the key. The rock is “Run-of-Mine” (ROM). It is big and small mixed. We spray acid on top. The acid goes down. It dissolves the copper.

But there is a problem. The rocks are big. The acid cannot go inside. The recovery rate is low. It is often 40% to 50%. The time is long. It takes years. Sometimes 5 to 10 years. We check the International Journal of Rock Mechanics. Data shows this slow speed. It is cheap to start. But the return is slow.

What is Heap Leaching?

Heap leaching is different. It is for better ore. Maybe 0.5% to 2.0% copper. We must prepare the rock. This is vital. We crush the rock first. We make it small. Usually 12mm to 25mm. We use ZENITH crushers for this. We put the rock on a lined pad. We pile it neat. We spray acid.

The result is fast. The cycle is months. Not years. The recovery is high. It can be 70% to 85%. The acid touches more surface. This is because we crushed it. The cost is higher at first. You buy crushers. But profit comes fast. It is efficient.

Why is Crushing So Important?

You might ask why. Why spend money to crush? The answer is “Lamination Crushing”. This is a principle. We use it in ZENITH cone crushers. We break rock along natural cracks. This exposes the copper mineral.

We look at the CSS. This is Closed Side Setting. It controls the output size. If CSS is 20mm, the rock is small. Acid works better. We also check the OSS. This is Open Side Setting. It helps throughput. We balance them. A small CSS means fine product. Fine product means more copper. Why do we do this? To make money fast.

Core Equipment: The Jaw Crusher

The first step is the Jaw Crusher. It eats big rocks. It is a “tiger’s mouth”. We use the PE series. The principle is simple. A moving jaw presses the rock. It presses against a fixed jaw. The rock breaks.

Technical specs are key. The crushing ratio is big. It is 4:1 to 6:1. The motor power matches the flywheels. This saves energy. We use a toggle plate. It protects the machine. If iron gets in the plate breaks. The machine is safe. Why use it? It handles rough stone easily.

Core Equipment: The Cone Crusher

The second step is the Cone Crusher. This is critical for heap leaching. We recommend the ZENITH HST series. It uses hydraulic pressure. The principle is “inter-particle crushing”. Rocks crush rocks.

It has high speed. The main shaft spins fast. The eccentric distance is optimized. This makes a good shape. We want cubes. Not flakes. Cubes let liquid flow. Flakes stop the flow. The energy use is low. About 0.5 to 1.2 kWh per ton. Why choose this? It makes the perfect size for acid.

Comparison of Technical Parameters

Let us look at numbers. Data does not lie. We compare the two methods. We use a table below. It shows the difference clearly.

Q1: Why is my acid consumption so high?

This is a pain point. Many miners ask this. You spray acid. But copper does not come. The acid is gone. Why?

The answer is often “Fines”. Dust. If you have too much dust it blocks the flow. The acid pools on top. It evaporates. Or it reacts with waste rock. This is “Gangue Consumption”. The solution is better screening. Use a vibrating screen. Remove the dust. Or use agglomeration. Stick dust to big rocks. This saves acid. It saves money.

Q2: Why is the heap becoming impermeable?

You start well. Then flow stops. The heap is clogged. We call this “Compaction”. It is bad.

The cause is clay. Or soft ore. When wet it turns to mud. The solution is the crusher type. Don’t use a grinder. Use a compression crusher. Like the ZENITH Cone. It makes less dust. Also keep pile height low. Do not stack too high. 6 meters is good. 10 meters might crush the bottom. Air must flow too. Copper needs oxygen. No air means no copper.

Real Case Study: Peru Copper Project

Let’s look at a real site. A client in Peru. They had oxide copper. Grade was 0.8%. They used dump leaching first. Recovery was only 45%. They were losing money. They called ZENITH.

We changed the design. We added a crushing plant.Equipment List:PE-900×1200 Jaw Crusher.HST-250 Cone Crusher.3-Deck Vibrating Screen.

The Process:We crushed to P80 = 20mm. We removed the fines. We stacked it on a new pad.

The Result:Recovery went up. It hit 78% in 6 months. The client was happy. The operator said: “The ZENITH machine runs smooth. Maintenance is easy. We just change the liner every 4 months.” Energy cost dropped by 15%. This is a fact. We validated the data.

Installation and Maintenance

Machines need care. Like a car. Installation must be solid. Concrete foundation is a must. Check the level. If it vibrates it breaks.

For maintenance check the oil. The cone crusher needs clean oil. Dirt kills the bearing. Check the gap daily. The CSS changes as liners wear. You must adjust it. ZENITH machines have buttons. You press a button. The hydraulic ram moves. It adjusts the gap. Easy. No heavy tools needed. This solves the worry of downtime.

Common User Questions (FAQ)

Q: Can I switch from dump to heap?

A: Yes. But you need space. You need money for crushers. You cannot move the old dump easily. You start with new ore.

Q: How much power does the plant use?

A: It depend on the rock hardnes. Usually for crushing it is 2-3 kWh per ton total. It is a small cost compared to acid.

Q: How long do parts last?

A: Jaw plates last 3-6 months. Cone mantles last 2-5 months. It depend on silica content. High silica cuts metal fast.

Do not look only at cost. Look at value. A ZENITH plant cost money. But it pays back. Usually in 8 to 14 months. This is fast. The extra copper pays for it. If you get 20% more copper it is huge. The math is simple. High recovery wins.