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The Numbers From Retrofitted Plants Practice at a number of brick plants now provides a clear benchmark for closing process gaps. After converting an old two-stage flowsheet to a corrected configuration, the largest single change reported is in the raw material preparation section: hourly output rises by roughly 25 percent, while production cost in that same section falls by about 15 percent. Those two figures move in opposite directions for a reason. Higher output comes from removing the cushioning fines and the pointless recirculation; lower cost comes from spending energy once on material that genuinely needs reducing. Neither improvement depends on running the line harder. Reported Retrofit Results IndicatorBefore RetrofitAfter Retrofit Hourly output, raw material sectionBaselineUp approximately 25% Production cost, raw material sectionBaselineDown approximately 15% Crusher dutyMixed feed plus circulating loadMatched to stage design Downtime tied to the bottleneckFrequentReduced Why Owners Resist, and Why the Logic Is Changing Brick plants are currently operating under severe pressure. Many have closed, and those still running are doing so on thin margins. Every owner knows where the defects in the process sit. Yet most decline to fix them, and the reasoning is understandable: a retrofit requires capital, and money already earned is difficult to commit to an enterprise that is not currently earning well. That reasoning treats the retrofit as an expense. In the current market it is more accurately understood as the cost of remaining competitive. The same argument applies at the level of the individual plant and at the level of the industry. The Health Argument There is a simple analogy worth considering. The only reliable route to a long life for a person is a strong and healthy body; nothing else substitutes for it. A business is no different. An enterprise that intends to survive long term must first make itself structurally sound, so that when a crisis arrives it can clear obstacles that stop others. When a plant's production cost sits at the lowest level in its region, it gains something more valuable than profit: room to manoeuvre. That margin of survival, not the profit line, is what decides which plants remain operating after a downturn. What the Shift in Cost Means In the earlier market: production cost determined how much profit a plant made. In the current market: production cost determines whether the plant continues to exist. Treating the Flaw as Capital, Not Expense A flawed flowsheet is not a fixed characteristic of a plant. It is a design inheritance that can be corrected, and the corrections available are well documented: screen ahead of the secondary crusher, or add a dedicated third stage to eliminate circulating load. The economics are no longer marginal. A 25 percent gain in preparation output and a 15 percent reduction in preparation cost compound across every operating hour of every year that follows the retrofit. Set against that stream of savings, the capital outlay is best understood as buying back capacity the plant already paid for once, and never received.

When Screening Ahead Is Not Enough Front-loading the screening duty removes fines from the secondary crushing chamber, but it does not by itself resolve the second diagnosed cause: coarse screen oversize returning to a crusher sized for much larger feed. Where that circulating load remains the binding constraint, a third crushing stage is the appropriate correction. Its defining feature is simple: screened material no longer returns to the secondary crusher at all. The Revised Stage Sequence In a three-stage arrangement, the secondary crusher is relieved of the recirculating stream. Oversize from the screen is directed to a dedicated third-stage crusher whose chamber geometry, hammer configuration and speed are matched to the 2 to 20 mm feed it actually receives, instead of being forced through a machine designed around primary product. Because each stage now works on the size range it was engineered for, the plant recovers the three benefits that a misapplied single machine destroys: efficient energy transfer per strike, a stable and predictable product curve, and a screening operation that is no longer fighting a stream it cannot classify cleanly. Secondary Versus Third Stage: Matching Machine to Duty AspectSecondary Crusher on Coarse ReturnDedicated Third-Stage Crusher Feed size rangeMostly 2-20 mm, far below designMatched to the fines-removed oversize Impact efficiencyPoor, hammer bypasses small lumpsHigh, chamber grips the feed Circulating loadGrows with each passLargely eliminated Hourly output of the stageDepressed by repeated reworkRaised substantially Engineering Checks Before Committing Verify available headroom and footprint for a third machine and its drive. Confirm the third-stage product curve meets the fineness your forming line requires. Re-balance the screen aperture set so each deck sends material to the correct stage. Re-tier conveying and dust collection across three stages rather than two. What Changes on the Production Floor The most immediate and measurable change is on the secondary crusher itself. Relieved of the return stream, it operates within its intended load envelope, its hourly output rises sharply, and the whole preparation section stops queuing behind it. Downstream units that were previously starved of material begin to run at their own rated capacity, which is where much of the system-level gain is realised. Energy follows the same logic. Work that was previously repeated on the same material is now performed once, at the stage designed for it. Specific power consumption per tonne of prepared material falls even though one more machine has been added to the line. Choosing Between the Two Remedies Screening ahead and three-stage crushing are not competitors. The first is the lower-investment correction for fines contamination and suits plants with usable free space before the secondary stage. The second addresses circulating load directly and suits plants where the return stream is the dominant constraint, or where a finer final product is required. Both share the same underlying principle, and it is the principle that matters more than the specific layout: never ask one machine to do work that belongs to a stage it was not designed for.

Close the Gap at the Source If fines entering the secondary crushing chamber are the root of the capacity loss, then the most direct correction is to stop them entering at all. The first and most widely adopted remedy does exactly that: install a double-deck screen and move the screening duty ahead of the secondary crusher, rather than leaving it downstream. How the Revised Flowsheet Works In the corrected arrangement, material leaving the primary crusher is screened before it reaches the secondary stage. The double-deck configuration splits the stream into a fine fraction that bypasses secondary crushing entirely and a coarse fraction that proceeds to the crusher. The result, visible in the revised process diagram, is that only one type of material enters the secondary machine: screened oversize, with no fines mixed in and a substantially lower total mass flow. Two changes follow immediately. The cushioning effect disappears, because there is no fines bed to absorb impact energy around the lumps and hammers. And the volumetric load on the chamber drops, so each hammer strike meets material it can actually grip and break. What the Plant Gains ParameterOriginal Two-Stage FlowsheetScreening-Ahead Flowsheet Feed composition to secondary crusherMixed coarse plus finesScreened oversize only Impact energy efficiencyReduced by fines cushioningRestored to design level Mass flow through crusherFull primary productCoarse fraction only Total system throughputLimited by crusherRaised substantially The duty assigned to the secondary crusher is reduced on two fronts at once, by composition and by tonnage. That combination is why plants report a significant overall increase in the handling capacity of the whole crushing system, rather than a modest incremental gain. Implementation Points Worth Planning For Size the double-deck screen for the full primary product flow, not for the post-split fraction. Provide a clean bypass route for the fine fraction so it reaches mixing without re-entering the crusher. Review dust collection at the new screening point, since a dry fine stream is now liberated earlier in the line. Confirm that the crusher discharge and the bypass stream rejoin at a point where blending remains consistent. Why This Route Suits Existing Plants Screening ahead of crushing is attractive to operating plants because it does not require replacing the crusher. It inserts one well-understood unit operation into an existing line, keeps the installed crusher in service, and converts an overloaded machine into one working within its design envelope. It also addresses both diagnosed causes in a single move: the fines never reach the chamber, and the coarse return stream shrinks because the screen has already removed what did not need crushing. For plants where the layout allows an additional screening station, this is typically the shortest path from a bottleneck to a balanced line, and it is the option most frequently validated in retrofit projects.