No extra gold is being put back in the river because they removed the top sluice. Bottom line.
Typically the sluices on the dredge are used for gold recovery and black sands are scrapped. Each time the material goes through a sluice it is called 'upgrading' because the quality of the material is upgraded.
The dredges pump the material to the lower sluice which drops back sand and gold into the sump because of their specific gravity(upgraded). Then the second onboard pump moves the concentrates in the sump to the upper sluice to 'upgrade' it again. This is where black sands could be lost if the company did not remove the top sluice. The top sluice would catch the gold but eventually begin to let the black sands flow back into the river. This would leave to a high quality gold concentrate on the top sluice but very little black sands.
By removing the top sluice the company has effectively stored or stockpiled everything in the sump so they can separate it without waste. With the new equipment they will be able to extract gold without pumping the black sands back into the river. In essence, yes this is the best configuration for the company. by removing the top sluice the company is able to pull the most valuables from the river. The only downside is the need for further processing since it is all lumped together.
Hope this helped, maybe someone else can explain it better.
Don't argue with idiots. They just drag you down to their level and beat you with home court advantage.
