Lithium Selective Adsorbent of Suqing SQ-06Li

The SQ-06Li lithium extraction adsorbent developed by Suqing is a new polymer synthetic material product. On the basis of the first generation of lithium adsorbent has made great improvements, using new nanomaterials, composite pore-forming agent and special granulation process, the appearance of regular (spherical, the industry only), large specific surface area, high selectivity, the performance is significantly improved, the adsorption capacity is 50-60% higher than similar products under the same conditions, At the same time, the product has the advantages of convenient elution, high resolution rate, low dissolution loss rate and good durability, and the product performance has achieved a qualitative leap.

▲PhysicalandChemicalProperties:

Trend diagram of lithium adsorption capacity of SQ-06Li in different brines

▲Pretreatment:

In order to ensure that the trace oligomers that may exist in the new adsorbent and the impurities brought in during the filling process are removed without affecting the quality of the product, the following pretreatment operations should be performed before the new adsorbent is officially used:

(1) Backwashing: After the adsorbent is filled, firstly perform backwashing with clean water (or in a special treatment tank for adsorbents), and the flow rate is controlled at 7-10BV/h (bed volume/hour) to ensure 70% backwashing Expansion rate to remove impurities and tiny particles until the backwash water is clarified, which takes about 0.5 hours;

(2) Soaking: Stop backwashing, lower the liquid level to 20cm above the highest point of the adsorbent layer, and soak for about 2 hours to make the adsorbent fully fall into the bed;

(3) Washing: finally rinse the bed with deionized water at 3-4BV/h, which takes about 3-5 hours.

★Single-column test

▲Adsorption：

A certain volume of adsorbent V(mL) is loaded into the exchange column, a certain volume of brine V0(L) is taken, and the brine (C0, mg/L) is controlled to pass through the adsorption column in 0.5-5BV/h downstream to collect the effluent, monitor the lithium concentration at the outlet of the adsorption column, and stop feeding after the adsorption equilibrium. The adsorption volume of the tail halide is V1 (L), and the concentration of the tail halide mixed lithium is detected C1 (mg/L).  

▲Replacement：

Lower the liquid level to the highest level of the adsorbent layer, and replace the residual brine with low calcium magnesium lithium brine at 2BV/h downstream. It takes 0.5 hours to collect and replace the brine, measure the volume V2 (L), and detect the concentration of lithium in the brine C2 (mg/L).

▲Desorption：

Co-current elution of the adsorbent bed with deionized water at 2BV/h. It takes about

1. 5-5 hours (sampling every hour to monitor the lithium concentration is recommended).When the lithium concentration of the eluent was lower than the design requirements, the elution was stopped, the total volume of the eluent was measured at V3 (L), and the concentration of the eluent mixed lithium at C3 (mg/L) was detected.

▲Repeatthestepsofadsorption,displacement,andelutionforcyclicoperation

According to the formula, the lithium adsorption capacity, elution capacity and yield are calculated respectively:

lithium adsorption capacity: Q₁（g/L）= [C₀*V_O-C₁*V₁-C₂*V₂]/V

                    elution capacity: Q₂      (g/L)  = C₃*V₃/V

                                       yield : R  = Q₂/Q₁*100%

★Continuous ion exchange technology

▲Adsorption：

     Adsorbent (single column volume V,mL) was filled according to the design quantity, adsorption flow rate q1 (mL/min) and switching time t(min) were set, brine C0 (mg/L) was controlled for downstream adsorption, and tail halide concentration C1 (mg/L) was collected for detection.

▲wash：

Set the leaching flow q2 (mL/min), and wash the adsorbent with low calcium magnesium brine (eluting front section) downstream.

▲Desorption：

Set elution flow rate q3 (mL/min), time t1 (min) before elution, and time t2 (min) after elution. Eluent is eluted with deionized water downstream, and eluent is collected in stages. Although the elution stage (i.e. low calcium and magnesium brine) is high in lithium, the content of calcium and magnesium is not up to the standard, it is used to wash the adsorbent in the washing section. The liquid in the post-analytical section had low calcium and magnesium content and high lithium content. The liquid in the post-analytical section was collected for detection of lithium content C2 (mg/L).

▲Replacement water：

Set the replacement water flow rate q₄ (mL/min), and use brine countercurrent to push out the water in the adsorption column.

lithium adsorption capacity:Q₁（g/L）=(C₀-C₁)*q₁*t/1000V

elution capacity:                      Q₂（g/L）=C₂*q₃*t₂/1000V

yield:                                          R    =Q₂/Q₁*100%

▲Matters needing attention：

It may be due to the following reasons that the leakage of lithium in the effluent will increase and the amount of lithium in the elution will decrease. Usersdo the trouble shooting accordingly:

1. Lithium leakage in effluent increased or adsorption capacity was low:

(1) The new resin is not pretreated as required, and the lithium residue in the pore affects the adsorption effect;

(2) The inlet and outlet valves are leaking, and the inlet water leaks into the outlet water. check the tightness of the valves;

(3) The adsorption flow rate is too fast, the contact time of the adsorbent with the brine solution is not enough, and the exchange is not complete. adjust the adsorption flow rate to the normal value;

(4) Check whether the adsorbent column is empty, control the balance of incoming and outgoing water flow and keep the water level in the column;

2. The amount of lithium in elution is reduced:

(1) The amount of water used to elute is insufficient and does not reach the standard of 10-20BV;

(2) The water quality of the elution water is too poor or the salt content is too high, and the quality of the water used should be improved;

(3) The elution time is too short for the lithium to be desorbed, so the elution time needs to be strictly controlled;

(4) The adsorbent is agglomerated, and the adsorption effect is not good, resulting in bypass flow, resulting in poor regeneration effect. Strengthen the backwash effect, and control the appropriate backwash expansion rate and backwash time.

3. The continuous ion exchange adsorption capacity and yield are low

(1) The adsorption flow rate and time are not set properly, the flow rate is too fast and the switching time is too short;

(2)The series-parallel mode is unreasonable;

(3) The eluting section flow is set too fast, the early period is too long, and the distribution is unreasonable.