I am familiar with https://www.911metallurgist.com/blog/sequential-cu-pb-zn-flotation

No cyanide.

Anyone else can help?

yes https://en.wikipedia.org/wiki/Sodium_metabisulfite

Your comments don't mention the effect of particle size on zinc displacement. It is important to determine the particle size that reduces partially the zinc activation and the copper recovery is acceptable. 

Other important information can be obtained from a mineralogical study, basically, the optimum liberation between chalcopyrite and zinc sulphides. The presence of locked particles should be studied to evalute the effect of particle size on the copper recovery and zinc displacement.

You performed five flotation tests. What is the zinc displacement? Did you perform kinetics tests to evaluate the optimum copper rougher flotation time? It is important to konw if the zinc activation is high in the first seconds or in the last minutes. 

Time of flight secondary mass spectrometry (ToF-SIMS) can provide information on elements reported in the sphalerite surface and chalcopyrite. In this it is possible to detect the possible activator agent. Based on the results, the addition of EDTA should be evaluated to precipitate the activator agent.

Other point to consider is the collector and how to add the collector in the copper rougher tests. for example, if you added PAX during the conditiong stage, and you decided to add more PAX after two or four minutes, you can promote the flotation of zinc sulphides, specially if there are locking particles of chalcopyrite and sphalerite.  

If the flotation feed size is very fine, the selectivity is more complex. Also, you add the problem of entrainment and more gangue would be reported in the rougher concentrate. If the rougher concentrate has not good quality, the clening circuit would be more complex to operate.

You have a high grade ore, so, try to use a weak collector is not appropriate. The addition of SIPX could be considered. The addition of A3418 alone or combined with SIPX is other alternative.

If the pyrite content is not high, there would be more problems to get selectivity between chalcopyrite and sphalerite. 

You mentioned the presence of marmatite. Usually, marmatite can be determined by mineralogical studies or following a very specific analytical procedure. If there is black marmatite and the fraction of marmatite is hiigher than sphalerite, the zinc concentrate would have a serious problem, the iron content.

It is necessary and important to know the source of zinc activation in the copper rougher flotation circuit, otherwise the laboratory will not use the right methodology to minimize the problem. 

The flotation method is mainly to vulcanize copper oxide minerals first, then add copper complexing agents to form a stable lipophilic mineral surface, and then use neutral oil emulsion to cover the mineral surface.

surface, resulting in a highly hydrophobic floatable state, so that minerals can be firmly attached to the bubbles to complete the selection.

Emulsion flotation includes three aspects:

First, it is necessary to use selective organic copper complexing agent compounds, such as benzotriazole toluoyl triazole, mercaptobenzothiazole, diphenylguanidine, etc.;

One is to re-add non-polar oil emulsion to improve the adhesion between minerals and air bubbles. Non-polar oil emulsifiers include gasoline, kerosene and some oils, etc.

Third, selective inhibitors such as acrylic polymers and sodium silicate are required.

https://uwas.org/news/47.html

Sequencial float:

Assuming all the physical parameters are ok, try to do float tests with SMBS at lower pH values between 4 and 6.5 and target 8kg/t of ore or less to depress Zn and float Cu. refloat Zn using coppersulphate with PAX.