Addition Of Collector Research Articles

Flotation of ultra-low ash coal combined with ultrasonic pretreatment

ABSTRACT Ultra-low ash coal is an essential clean energy and material. The preparation of ultra-low ash coal by flotation is facing challenges due to the inherent drawbacks. This work aims to enhance the flotation efficiency of ultra-low ash coal by ultrasonic pretreatment. Timed-release flotation experiments were conducted with ultrasonic pretreatment before and after collector addition. The results showed that the recovery and combustible recovery and flotation perfect index of clean coal increased after ultrasonic pretreatment. Additionally, the flotation circuits can reduce from three to two times to obtain clean coal with ash content around 5%. The particle size distribution of coal varied from unimodal to bimodal after ultrasonic pretreatment no matter whether collector was added, indicating that ultrasonic had both dispersing and flocculation effects. Scanning electron microscope (SEM) analysis illustrated that the surface of coal was cleaned due to the ultra-fine gangue particles coated on coal surface was dispersed, and the flocculation of low-ash coal particles was promoted after ultrasonic pretreatment. Consequently, the ultra-low ash coal with higher recovery and quality could be obtained with simplified circuits.

Analysis of the Use of Family Information System Applications for Family Planning Counselors in West Sumbawa Regency

The objectives of this research are: 1. To determine the development of the Family Planning (KB) Program in West Sumbawa Regency. 2. To analyze the effect of using the Family Information System application on the quality of Family Planning (KB) extension services in West Sumbawa Regency. This research uses a mix of methods, namely quantitative methodology using infere statistical analysis and qualitative methods using descriptive methods, where this research was conducted to fully or clearly describe the Family Information System Application Innovation for Family Planning Counselors in West Sumbawa Regency. There are generally two types of data, namely quantitative data and qualitative data which will be explained below. The author uses quantitative and qualitative data in carrying out this analysis. Data sources are all forms of information in the form of data. The population in this study were Family Field Officers (PLKB) or Extension Officers spread across 8 (eight) Districts of West Sumbawa Regency. In this study, the sample was 1 (one) person who was responsible as a Family Information System (SIGA) officer at the Family Planning Extension Office (PKB) in 8 (eight) sub-districts. Data collection procedures in research are documentation, questionnaires, interviews and observation. The research results show that the problem of delays in the distribution of monthly reports is a top priority to be resolved. In order for the distribution of this monthly report to run smoothly, the following steps need to be taken: education for data collection officers in villages and sub-districts about the importance of monthly reports being sent on time to districts so that PKB and District Data Managers can report to BKKBN on time, there needs to be supervision the process of sending monthly reports starts from the village, sub-district and district levels so that if problems occur they can be handled immediately, and increasing the number of data collection officers and data managers so that the data collection process can be carried out quickly so that monthly reports can be sent on time. Conclusion on the criteria for data management using the optimal SIGA application. The flow of data and reports from villages, sub-districts, districts and the center or vice versa can run on time and there are no data errors. Data processing officers understand how to use the SIGA application. Suggestions include: In order for the distribution of monthly reports to run optimally, support from data processing officers, internet networks and SIGA servers is needed, SIGA application data is valid, data checking, maintenance and backup processes are needed, efforts can be made to optimize data management using applications SIGA. Addition of data collectors and data managers who have an IT educational background. Periodic SIGA application training for data processing officers, the integration process of three subsystems, namely contraceptive services, field control and family data collection and SIGA application development must be completed immediately and increase the capacity and speed of the SIGA Server and increase internet connection bandwidth

Advances in the Separation of Graphite from Lithium Iron Phosphate from End-of-Life Batteries Shredded Fine Fraction Using Simple Froth Flotation

Olivine-type lithium iron phosphate (LiFePO4, LFP) lithium-ion batteries (LIBs) have become a popular choice for electric vehicles (EVs) and stationary energy storage systems. In the context of recycling, this study addresses the complex challenge of separating black mass of spent LFP batteries from its main composing materials to allow for direct recycling. In this study, 71% copper and 81% aluminium foil impurities were removed by sieving black mass to <250 µm. Next, the application of froth flotation as a separation technique was explored, examining the influence of chemical agents, pre-treatment, and multi-step processes. Frother agent addition improved material recovery in the froth, while collector addition influenced the separation efficiency and enhanced graphite recovery. Pre-treatment, particularly sonication, was found to break down agglomerates and further improve separation. Multi-step flotation increased the purity of recovered fractions. The optimized process for a black mass < 250 µm, involving sonication pre-treatment and double flotation, resulted in enriched carbonaceous material (80.3 mol%) in froth fractions and high LFP concentration (81.9 mol%) in tailings fractions. The recovered spent LFP cathode material contained 37.20 wt% Fe2P2O7, a degradation product of LiFePO4. This research offers valuable insights for the development of efficient battery recycling methods for LFP batteries.

Aerosol collector addition in flotation – evaluation of delivery options

In conventional flotation systems, the collector is adsorbed onto mineral particles from the aqueous phase at the solid/liquid interface. Aerosol collector addition is a concept whereby collector molecules are introduced to mineral surfaces via the surfaces of bubbles or the solid/gas interface. Several studies have demonstrated this concept, ranging from the analysis of ideal mineral surfaces to laboratory-scale flotation of complex water systems. However, the physical addition of a collector to the surfaces of bubbles is not a common process and has no uniform methodology. If aerosol collector addition is to be studied as a viable reagent addition technique, it becomes necessary to develop and test appropriate methods that could be replicated across several different studies. This work examines two aerosol addition methods: a conventional Venturi-style gas liquid nozzle, as well as a purpose-built atomiser developed for use in pharmacological applications. Both were compared to a standard “upfront conditioning” batch dosage method and were found to be safe, simple to use and produced comparable flotation outcomes.

A rest potential study of impurity (As, Au, Ni and Co) bearing synthetic pyrite in alkaline flotation conditions

Pyrite is an important mineralogical component of most sulphide ore deposit classes, where it commonly forms part of the gangue mineralogy, but may also represent an important ore mineral (i.e., auriferous pyrite). Effective and efficient separation of pyrite is thus a crucial step during most ore processing operations, and this is in part influenced by the pyrite mineral chemistry. Here, electrochemical measurements were used to study the reactivity of a series of well-characterised synthetic trace-element substituted pyrite samples under alkaline conditions relevant to industrial flotation. The presence of metals and metalloid impurities (As, Au, Co, and Ni) in pyrite were tested using rest potential measurements to infer oxidation and associated hydrophobicity. In the absence of any collector phases, pure- and Ni-substituted pyrite have the highest rest potential, followed by Co-substituted pyrite and couple-substituted (Co + Au) pyrite, whilst As-substituted pyrite has the lowest measured rest potential. Importantly, the degree of oxidation at the mineral surface correlates linearly with the concentration of each of the substituents, with the largest effect observed when As is the substituent. These results correspond to the semiconducting properties and noble character of each pyrite sample, with n-type pyrite (Au-, Co- and Ni-substituted) associated with noble character and high rest potential, whereas p-type As-substituted pyrite associated with least noble character and lowest rest potential. With the addition of a potassium amyl xanthate collector, the mineral chemistry further had an impact on the probability of dixanthogen formation. Increased substituent concentration in the pyrite lattice decreased the probability of dixanthogen formation, except in a sample where high Au (and moderate Co) was incorporated. These results highlight the importance of developing improved understanding of the impacts of substitution mechanisms on the surface reactivity and flotability of pyrite. Such an understanding will form the foundation for further improved (and engineered) approaches towards reagent design and mixture. This will serve to optimise separation of both gangue and valuable pyrite by using fundamental knowledge to target specific collector bands and flotation domains.

Experimental investigation and performance evaluation of spiral and serpentine collectors based photovoltaic thermal system in Peninsular Malaysia

Photovoltaic thermal (PVT) systems have been developed for nearly five decades as a further development of PV technology. The PVT system was designed to overcome the limited space for PV and solar water heaters and improve PV cell performance. However, many studies on PVT are theoretical and modeling, so experimentation is needed to confirm it. This study investigated the performance of PVT systems with a spiral and serpentine thermal collector without metal sheets in two scenarios, without and with insulation. Commercial PV was modified with the addition of a copper tube thermal collector and tested with a comparison PV under the weather of the Malaysian peninsula. The experimental results show a maximum electrical efficiency enhancement of 0.53% and a decrease in module temperature up to 5.60 °C in scenario 1. Also, the addition of insulation in scenario 2 increases thermal efficiency up to 18.26%, even though it causes a decrease in electrical efficiency. This research shows that an uncomplicated thermal collector is adequate to increase the electrical efficiency of PV panels. In contrast, the addition of insulation in the rear side of the PVT panel increases the thermal performance of PVT systems.

Investigation of the effect of a solar collector, nozzle, and water cooling on solar still double slope

Many nations, particularly those in rural places, are struggling with the freshwater crisis. Recently the best way to produce freshwater is done with solar still. In this study, four different solar stills were built and were labelled as conventional solar still (SSA), solar still with the addition of water cooling on the glass cover (SSB), solar still with the addition of a nozzle inside the solar still (SSC), and solar still with the addition of a solar collector (SSD). The four solar stills will be evaluated and compared under the same environmental conditions in Medan City, Indonesia (Latitude/Longitude/: 3° 47' 3.4908'' N/98° 41' 39.1956'' E). The temperature, freshwater productivity, exergy, energy, and economic analysis will be studied for the four solar stills. From the data, the glass temperature of SSC was higher than SSA in the range 08.00 -11.30. SSD was found to have the highest average energy and exergy efficiency. SSB has successfully increased freshwater production by 28.9% from 0.81 L/m2/day to 1.0436 L/m2/day. Moreover, SSB has the lowest cost compared to other solar stills, which only cost 0.193 $/L/m2.

The utilization of BHA and SBX collector mixture for the flotation of moderately oxidized pyrrhotite

The benzohydroxamic acid (BHA) and sodium butyl xanthate (SBX) mixture was used as a collector for the flotation of moderately oxidized pyrrhotite (MOP) in this work. Microflotation results revealed that the flotation recovery of MOP was not very high with the addition of individual SBX or BHA collector, but significantly improved using a mixed collector of SBA/BHA, the maximum flotation recovery of could reach 88.55%. Zeta potential measurement revealed that the surface charges of MOP were negatively moved after the addition of mixed SBX/BHA compared to adding SBX or BHA alone, revealing a much stronger interaction between the collector mixture and MOP surface, leading to the improvement of MOP floatability. The FTIR spectra analysis revealed that the synergistic effect of SBX/BHA was attributed to the interaction between BHA and MOP, which could reduce the hydrophilic Fe(OH)3 on the pyrrhotite surface, allowing more adsorption of SBX onto the generated fresh unoxidized surfaces.

FARKLI EĞİM AÇILARINDA GÜNEŞ KOLLEKTÖRLERİNİN ENERJİ VE EKSERJİ ANALİZİ: ERZİNCAN İLİ ÖRNEĞİ

Güneş kollektörleri kullanım suyu ısıtma uygulamalarında sıklıkla kullanılmaktadır. Tasarım aşamasında güneş kollektörlerinin en uygun eğim açısında konumlandırılması güneş enerjisinden verimli faydalanılması için önemlidir. Bu çalışmada, Erzincan ilinde konumlandırılan bir güneş kollektörünün eğim açısının aylık/günlük ortalama ışınım değerlerine, su çıkış sıcaklığına, enerji ve ekserji verimlerine etkisi teorik olarak incelenmiştir. Optimum güneş kollektörü eğim açısının en yüksek ve en düşük değerlerinin Aralık ve Haziran aylarında sırasıyla 63° ve 0° olduğu görülmüştür. Erzincan için önerilen (27.14°) ve hesaplanan eğim açıları için günlük ortalama saatlik ışınım değerleri karşılaştırılmış olup en büyük değişimin Ocak ayında %26 olduğu görülmüştür. Buna ek olarak, güneş kollektörünün enerji ve ekserji verimleri hesaplanmış olup optimum eğim açıları için en yüksek verimleri sırasıyla %74.2 ve %9.7 olarak belirlenmiştir.

A study on the recovery of fine chromite from UG2 tailings

The recovery of chromite from the tailings streams of South African UG2 platinum concentrators adds significant financial returns to these operations. Whilst the coarser fractions are amenable to processing by physical separation, the focus is now also on the recovery of fine (typically −75 µm) chromite by flotation.This paper describes the results of a series of physical separation, and chromite bench flotation tests that have been carried out at acidic and natural pH respectively, on UG2 tailings from Pilanesberg Platinum Mines (PPM) on the western limb of the Bushveld Complex in South Africa. The objective of the work is to find a route that would best produce, from a feed assaying around 18 % Cr2O3 and with 50 % of the chromite in the −38 µm fraction, a concentrate of at least 40 % Cr2O3 and an overall yield of more than 13 %.Results showed that shaking tables and wet high intensity magnetic separation (WHIMS) alone were not capable of upgrading the tailings to the target grade. However, flotation tests at a pH of 2.5 on a sample that was deslimed at 10 µm by cycloning, as well as a sample that was screened at 25 µm and subjected to WHIMS, demonstrated that a product assaying 42 % Cr2O3 could be attained at yields between 8 and 11 %, with recoveries ranging between 19 and 27 %. The results highlighted the importance of desliming prior to flotation, in reducing the dosage of the Flotinor V-2711 collector by more than 60 %.Subsequent flotation tests at natural pH on hot tailings samples with two stages of cleaning showed good upgrading, where a feed grade of 16.1 % Cr2O3 after desliming was converted to a concentrate of 29.4 % Cr2O3 at a yield, based on deslimed feed, of 28.6 % and a recovery of 52.4 %. The overall upgrade ratio in this case of 1.83 was slightly lower than those of the acidic tests (i.e., 1.87 and 2.31 respectively) but also at lower yields (28.6 % vs 33 %) and recoveries (52.4 % vs 62 %). Further work is underway to investigate various flowsheet options, including the flotation of fines spiral concentrates, staged collector addition to the cleaning stages, and froth washing.

Separation of silicon carbide and silicon powders in kerf loss slurry of loose abrasive sawing by means of phase transfer separation method with mixed cationic-anionic surfactant collectors addition

Kerf loss slurry generated from the slicing process of silicon wafer by using loose abrasive sawing method contains silicon carbide (SiC) and silicon (Si) powders. This study attempted to separate SiC and Si powders in kerf loss slurry through phase transfer separation method with mixed cationic-anionic surfactant collectors addition. Isooctane and water were employed as the two phases. Dodecylamine acetate (DAA) and sodium oleate (NaOL) was used as the cationic and anionic surfactant collector, respectively. The effects of single surfactant collector addition (DAA/NaOL) and mixed cationic-anionic surfactant collectors addition (DAA + NaOL) on the transfer of individual SiC and Si powders from the water phase to the isooctane phase, as well as on the separation of SiC and Si powders in kerf loss slurry, were investigated and compared.The results indicated that DAA could improve the transfer of both SiC and Si powders to the isooctane phase, and the improvement for SiC powder was higher than for Si powder. In contrast, NaOL could only improve the transfer of SiC powder to the isooctane phase, and the improvement for SiC powder was less than DAA did. Compared to single DAA/NaOL addition, mixed DAA + NaOL addition could improve the separation of SiC and Si powders in kerf loss slurry at lower surfactant collector dosages. In addition, the dosage of NaOL in mixed DAA + NaOL addition had more significant effect on improving their mutual separation than that of DAA did. The optimal separation results were obtained with mixed surfactant collectors addition of 0.01 kg/ton DAA and 0.05 kg/ton NaOL at pH 5. The purity and recovery of SiC powder recovered from the isooctane phase was 90.0% and 92.0%, respectively, and those of Si powder recovered from the water phase was 89.5% and 87.0%, respectively. The total dosage of surfactant collectors was 40% reduced.

Differential flotation of pyrite and Arsenopyrite: Effect of pulp aeration and the critical importance of collector concentration

• Differential oxidation of pyrite and arsenopyrite achieved with pulp aeration. • Recovery of pyrite and arsenopyrite was high when singularly treated. • Xanthate adsorption removed high FeOOH removal from arsenopyrite compared to pyrite. • Adsorption of xanthate on heavily oxidised arsenopyrite surface was slow. • Selectivity was lost at high xanthate concentration. Differences in the oxidation rate and extent of model pyrite and arsenopyrite minerals, augmented by pulp aeration, was investigated using dissolved oxygen demand tests and X-ray photoelectron spectroscopy (XPS) analysis. Flotation studies of single mineral admixture coupled with zeta potential measurements, UV–Vis spectroscopy analysis of collector concentration and ex-situ metal ions in solution after collector addition were ascertained to shed light on reasons for observed window for selective flotation. The highest selectivity was achieved with low collector concentration of 1 × 10 -5 M PAX and selectivity index of 5.2 after 6 min flotation with collector concentration playing a critical role in attaining a good selectivity. Fast adsorption of xanthate and simultaneous oxidation to dixanthogen on slightly oxidised pyrite surface starved heavily oxidised arsenopyrite surface of the collector species, at low collector concentration, leading to its depression. The study was extended to the flotation of an auriferous refractory ore where similar observations were made. 62.7% rejection of pyrite was achieved in the staged flotation process.

Effect of mixed collector addition sequence on the adsorption behavior of low-rank coal surface: Experimental and molecular dynamics simulation study

The effect of addition sequence for mixed collectors comprising of dodecane(D) and n-valeric acid(A) on low-rank coal flotation was explored by the following three sequences: D first and then A(D + A), A first and then D(A + D), D and A were added simultaneously(M). The total organic carbon, contact angle, zeta potential, and X-ray photoelectron spectroscopy results revealed that the coal had the highest adsorption capacity and the best hydrophobicity for the M, followed by A + D and D + A. The molecular dynamics simulation results indicated that for the M, the reagent molecules D and A worked together to facilitate the adsorption of the reagent molecules and solved some difficult-to-adsorb sites, not for the D + A and A + D. The M-type addition sequence would obtain the larger non-bonding interaction energy and more hydrogen bonds between collector molecules and the coal surface. Finally, the flotation experiments confirmed that the order of the flotation efficiency was M > A + D > D + A.

Performance analysis of a textile based solar assisted air source heat pump with the energy and exergy methodology

Solar air collectors are integrated into the air source heat pump in order to increase the performance of the heat pump in cold climate regions. The evaporator air is heated by solar air collectors. In this study, two different types of solar air collectors which were textile based solar air collector and flat plate solar air collector were used. The thermal energy stored in the tank during the day was used to heat the room at day and night. The thermal storage tank was heated using three heating systems, textile based solar assisted air source heat pump (TSAHP), flat plate solar assisted air source heat pump (FSAHP) and air source heat pump (ASHP). In this study, energy, exergy and economic analysis of three different heating systems were performed. COP values increased by 32% in TSAHP and 21% in FSAHP compared to ASHP. Addition of solar air collectors to the ASHP heating system has been shown to improve thermal storage tank performance. Total exergy efficiency values were calculated as 14.4%, 13.4% and 11.3%, for TSAHP, FSAHP and ASHP heating systems, respectively. Levelized cost of heating of novel type system (TSAHP) ($/kWh) was 11.8% lower than conventional ASHP.

A novel method for extraction of platinum from spent automotive catalyst: utilization of spent fluid catalytic cracking catalyst as flux

ABSTRACT A novel method of smelting of mixture of spent automotive catalyst (SAC) and spent fluid catalytic cracking catalyst (SFCC) to recover platinum and prepare glass slag was investigated. Compared to other metals collection processes for single hazardous waste solid, this method reduced the amount of fluxing materials addition and increased the processing types of hazardous solid waste simultaneously. The optimum SFCC addition, iron collector addition, Na2B2O4•10H2O addition, CaO/SiO2 mass ratio, temperature, and holding time for platinum recovery were 20, 11, 16 wt%, 0.6, 1550–1600°C, and 60 min, respectively. In this proposed combined process, more than 98% of platinum is efficiently recovered from SAC. Meanwhile, the concentration of platinum in glass slag was less than 7 g/t. The leaching characteristics of heavy metals in slag confirmed the obtained glass slag is a non-hazardous slag due to the low leaching rate of heavy metal ions. This article proposed an effective and environmentally friendly method for the recovery of platinum from SAC via a combined smelting process.

THE EFFECT OF REVERSE FLOTATION METHOD ON SILICA SAND AS WATERPROOFING MORTAR

THE EFFECT OF REVERSE FLOTATION METHOD ON SILICA SAND AS WATERPROOFING MORTAR. Waterproof fabrication mortar cement by silica sand using reverse flotation silica (RFS) method was evaluated by waterproof absorption coefficient, compressive strength test, attractive test, and contact angle. RFS is used to replace waterproof agent and aggregate mortar to reduce cost. The aims of this experiment are to know the RFS process, the ratio between waterproof mortar cement with RFS and mortar, to determine performance and characteristic waterproof mortar cement. Methods used are prepared RFS, mortar cement fabrication, and testing (compressive strength, tensile strength, permeability, contact angle, XRF, FTIR, SEM, BET). Variable used are ratio cement/silica sand, concentrations of CaCl2, curing time, oleic acid, and sodium oleate addition. Optimum collector addition is obtained by oleic acid with compress strength 167.65 kg/cm2, tensile strength 0.16 MPa, permeability 4.6 cm, and contact angle 95°. Curing inside water effect and outside temperature give compress strength 167.65 kg/cm2 and 163.24 kg/cm2, permeability curing inside the water and outside temperature are 4.6 cm and 12 cm. Optimum CaCl2 addition is gained at CaCl2 1.8M with compress strength 64.29 kg/cm2, tensile strength 0.15 MPa, permeability 2.4 cm, contact angle 95°. Optimum ratio cement/RFS is 1:1 with compress strength 167.65 kg/cm2, tensile strength 0.16 MPa, permeability 4.6 cm, and contact angle 950.

Critical analysis of metallic and non-metallic fractions in the flotation of waste printed circuit boards

The processing of e-waste is gaining importance worldwide as it contains a large number of valuable metals. In the present investigation, an attempt has been made to analyze the influence of surfactants on the flotation of printed circuit boards. Flotation kinetic studies have been carried out by varying different surfactant combinations such as C0F0 (without surfactants), C0F1 (only frother), C1F0 (only collector), and C1F1 (collector and frother). A first-order kinetic model has been proposed to explain the recovery of metallic and non-metallic particles. The hydrophobic plastic particles could be recovered to the froth products without surfactants. The addition of collector and frother imparts movement of few metallic particles to the froth products causing a decrease in the recovery of metals to the non-froth products (Cu recovery decreased from 92% to 72% and Sn recovery decreased from 90.1% to 65%). However, the frother is essential to impart stability to the froth and facilitate transportation of particles to the froth products. Frother alone can satisfactorily separate metallic and non-metallic particles.

Solar collector field and thermal energy storage for auxiliary component in organic rankine cycle for bottoming unit to utilize exhaust steam from back pressure turbine of Ulumbu geothermal power plant

Flores has a vast geothermal energy sources, one of the fields, Ulumbu, producing electricity from the geothermal power plant (PLTP). PLTP Ulumbu has two back pressure turbines generating 2.5 MW electricity. Besides geothermal power, Flores has potential solar energy sources that are recorded as much as 5 to 6 kWh/m2/day. The exhaust steam from the backpressure turbine adds the binary cycle as the bottoming unit. It is able to generate electricity continously to supply the baseload. Currently, the peak load of electricity usage in Flores is supplied by the diesel power plant (PLTD). This paper studies the addition of solar collectors and thermal energy storage (TES) as auxiliary components in the binary cycle and simulates the system by using the Aspen Plus. The solar energy is stored in TES during the day and then released to the heat exchanger in the evening. This idea reduces the dependency on diesel power plants in the evening. To increase power as much as 500 kW, the collector area needed to supply the system is 1.1 ha using synthetic oil as HTF. The volume of TES to stored the energy by using nitrate salts as HTF is 1,120 m3. As a result, the efficiencies of the non-hybrid system and hybrid systems are 11.38% and 11.31% subsequently.

Towards Understanding the Role of Surface Gas Nanostructures: Effect of Temperature Difference Pretreatment on Wetting and Flotation of Sulfide Minerals and Pb-Zn Ore.

Surface nanobubbles at hydrophobic interfaces now attract much attention in various fields but their role in wetting-related phenomena is still unclear. Herein, we report the effect of a preliminary contact of “hot” solids with cold water previously proposed for generation of surface nanobubbles, on wettability of compact materials and flotation of particulate galena (PbS), sphalerite (ZnS), and Pb-Zn sulfide ore. Atomic force microscopy was applied to visualize the nanobubbles at galena crystals heated in air and contacted with cold water; X-ray photoelectron spectroscopy was used to characterize the surface composition of minerals. Contact angles measured with the sessile drop of cold water were found to increase when enhancing the support temperature from 0 to 80 °C for sphalerite and silica, and to pass a maximum at 40–60 °C for galena and pyrite (FeS2) probably due to oxidation of sulfides. The temperature pretreatment depressed the recovery of sulfides in collectorless schemes and improved the potassium butyl xanthate-assisted flotation both for single minerals and Gorevskoye Pb-Zn ore. The results suggest that the surface nanobubbles prepared using the temperature difference promote flotation if minerals are rather hydrophobic and insignificantly oxidized, so the addition of collector and activator (for sphalerite) is necessary.

The Neutrally Buoyant Sediment Trap: Two Decades of Progress

AbstractThe biological carbon flux from the ocean’s surface into its interior has traditionally been sampled by sediment traps, which physically intercept sinking particulate matter. However, the manner in which a sediment trap interacts with the flow field around it can introduce hydrodynamic biases, motivating the development of neutral, self-ballasting trap designs. Here, the performance of one of these designs, the neutrally buoyant sediment trap (NBST), is described and evaluated. The NBST has been successfully used in a number of scientific studies since a prototype was last described in the literature two decades ago, with extensive modifications in subsequent years. Originated at Woods Hole Oceanographic Institution, the NBST is built around a profiling float and carries cylindrical collection tubes, a feature that distinguishes it from other neutral traps described in the literature. This paper documents changes to the device that have been implemented over the last two decades, including wider trap tubes; Iridium Communications, Inc., satellite communications; and the addition of polyacrylamide gel collectors and optical sedimentation sensors. Information is also provided with the intent of aiding the development of similar devices by other researchers, including the present adaptation of the concept to utilize commercially available profiling float hardware. The performance of NBSTs built around commercial profiling floats is comparable to NBSTs built around customized floats, albeit with some additional operational considerations. Data from recent field studies comparing NBSTs and traditional, surface-tethered sediment traps are used to illustrate the performance of the instrument design. Potential improvements to the design that remain to be incorporated through future work are also outlined.